<?xml version="1.0" encoding="utf-8"?>
<!--XBRL document created with Toppan Merrill Bridge  11.2.0.5 -->
<!--Based on XBRL 2.1-->
<!--Created on: 2/17/2026 3:01:11 PM-->
<!--Modified on: 2/17/2026 3:01:11 PM-->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#StatementConsolidatedStatementsOfFinancialPositionParenthetical" roleURI="http://principal.com/role/StatementConsolidatedStatementsOfFinancialPositionParenthetical" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#StatementConsolidatedStatementsOfStockholdersEquity" roleURI="http://principal.com/role/StatementConsolidatedStatementsOfStockholdersEquity" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesTables" roleURI="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesTables" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSeparateAccountBalancesTables" roleURI="http://principal.com/role/DisclosureSeparateAccountBalancesTables" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureContractholderFundsTables" roleURI="http://principal.com/role/DisclosureContractholderFundsTables" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsTables" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsTables" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureMarketRiskBenefitsTables" roleURI="http://principal.com/role/DisclosureMarketRiskBenefitsTables" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEmployeeAndAgentBenefitsTables" roleURI="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsTables" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureRevenuesFromContractsWithCustomersTables" roleURI="http://principal.com/role/DisclosureRevenuesFromContractsWithCustomersTables" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureNatureOfOperationsAndSignificantAccountingPoliciesContractholderAndPolicyholderLiabilitiesDetails" roleURI="http://principal.com/role/DisclosureNatureOfOperationsAndSignificantAccountingPoliciesContractholderAndPolicyholderLiabilitiesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureGoodwillAndOtherIntangibleAssetsChangesInGoodwillDetails" roleURI="http://principal.com/role/DisclosureGoodwillAndOtherIntangibleAssetsChangesInGoodwillDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureGoodwillAndOtherIntangibleAssetsFiniteLivedIntangibleAssetsDetails" roleURI="http://principal.com/role/DisclosureGoodwillAndOtherIntangibleAssetsFiniteLivedIntangibleAssetsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureGoodwillAndOtherIntangibleAssetsAdditionalInformationDetails" roleURI="http://principal.com/role/DisclosureGoodwillAndOtherIntangibleAssetsAdditionalInformationDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureGoodwillAndOtherIntangibleAssetsIndefiniteLivedIntangibleAssetsDetails" roleURI="http://principal.com/role/DisclosureGoodwillAndOtherIntangibleAssetsIndefiniteLivedIntangibleAssetsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureVariableInterestEntitiesConsolidatedViesDetails" roleURI="http://principal.com/role/DisclosureVariableInterestEntitiesConsolidatedViesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureVariableInterestEntitiesUnconsolidatedViesDetails" roleURI="http://principal.com/role/DisclosureVariableInterestEntitiesUnconsolidatedViesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsFixedMaturitiesDetails" roleURI="http://principal.com/role/DisclosureInvestmentsFixedMaturitiesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsNetInvestmentIncomeDetails" roleURI="http://principal.com/role/DisclosureInvestmentsNetInvestmentIncomeDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsAllowanceForCreditLossDetails" roleURI="http://principal.com/role/DisclosureInvestmentsAllowanceForCreditLossDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsGrossUnrealizedLossesForFixedMaturitiesDetails" roleURI="http://principal.com/role/DisclosureInvestmentsGrossUnrealizedLossesForFixedMaturitiesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsMortgageLoanCreditMonitoringDetails" roleURI="http://principal.com/role/DisclosureInvestmentsMortgageLoanCreditMonitoringDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsFinancingReceivableNonAccrualAndAgingDetails" roleURI="http://principal.com/role/DisclosureInvestmentsFinancingReceivableNonAccrualAndAgingDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsMortgageLoanValuationAllowanceDetails" roleURI="http://principal.com/role/DisclosureInvestmentsMortgageLoanValuationAllowanceDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsMortgageLoansDetails" roleURI="http://principal.com/role/DisclosureInvestmentsMortgageLoansDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsOtherInvestmentsDetails" roleURI="http://principal.com/role/DisclosureInvestmentsOtherInvestmentsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsSecuritiesPostedAsCollateralDetails" roleURI="http://principal.com/role/DisclosureInvestmentsSecuritiesPostedAsCollateralDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsBalanceSheetOffsettingAssetsDetails" roleURI="http://principal.com/role/DisclosureInvestmentsBalanceSheetOffsettingAssetsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureInvestmentsBalanceSheetOffsettingLiabilitiesDetails" roleURI="http://principal.com/role/DisclosureInvestmentsBalanceSheetOffsettingLiabilitiesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDerivativeFinancialInstrumentsNotionalAmountsAndCreditExposureDetails" roleURI="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountsAndCreditExposureDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDerivativeFinancialInstrumentsFairValueOfDerivativesDetails" roleURI="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsFairValueOfDerivativesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDerivativeFinancialInstrumentsCreditDerivativesSoldDetails" roleURI="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsCreditDerivativesSoldDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDerivativeFinancialInstrumentsFairValueHedgesDetails" roleURI="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsFairValueHedgesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDerivativeFinancialInstrumentsCashFlowHedgesDetails" roleURI="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsCashFlowHedgesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDerivativeFinancialInstrumentsEffectOfHedgesOnConsolidatedStatementsOfOperationsDetails" roleURI="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsEffectOfHedgesOnConsolidatedStatementsOfOperationsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDerivativeFinancialInstrumentsDerivativesNotDesignatedAsHedgingInstrumentsDetails" roleURI="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsDerivativesNotDesignatedAsHedgingInstrumentsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesAdditionalInformationDetails" roleURI="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesAdditionalInformationDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesDisaggregatedDacAmountsDetails" roleURI="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesDisaggregatedDacAmountsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesRetirementAndIncomeSolutionsBalancesAndChangesInDacDetails" roleURI="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesRetirementAndIncomeSolutionsBalancesAndChangesInDacDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesBenefitsAndProtectionBalancesAndChangesInDacDetails" roleURI="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesBenefitsAndProtectionBalancesAndChangesInDacDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesUnearnedRevenueLiabilityDetails" roleURI="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesUnearnedRevenueLiabilityDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesUnearnedRevenueLiabilityBalancesAndChangesDetails" roleURI="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesUnearnedRevenueLiabilityBalancesAndChangesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSeparateAccountBalancesSeparateAccountAssetDetails" roleURI="http://principal.com/role/DisclosureSeparateAccountBalancesSeparateAccountAssetDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSeparateAccountBalancesSeparateAccountLiabilitiesDetails" roleURI="http://principal.com/role/DisclosureSeparateAccountBalancesSeparateAccountLiabilitiesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSeparateAccountBalancesRetirementAndIncomeSolutionsDetails" roleURI="http://principal.com/role/DisclosureSeparateAccountBalancesRetirementAndIncomeSolutionsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSeparateAccountBalancesPrincipalAssetManagementInternationalPensionDetails" roleURI="http://principal.com/role/DisclosureSeparateAccountBalancesPrincipalAssetManagementInternationalPensionDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSeparateAccountBalancesBenefitsAndProtectionDetails" roleURI="http://principal.com/role/DisclosureSeparateAccountBalancesBenefitsAndProtectionDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureContractholderFundsDetails" roleURI="http://principal.com/role/DisclosureContractholderFundsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureContractholderFundsGicsAndFundingAgreementsDetails" roleURI="http://principal.com/role/DisclosureContractholderFundsGicsAndFundingAgreementsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureContractholderFundsChangesInPolicyholderAccountBalancesDetails" roleURI="http://principal.com/role/DisclosureContractholderFundsChangesInPolicyholderAccountBalancesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureContractholderFundsGuaranteedMinimumInterestRateDetails" roleURI="http://principal.com/role/DisclosureContractholderFundsGuaranteedMinimumInterestRateDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsDisaggregatedAmountsIncludedInFuturePolicyBenefitsAndClaimsDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsDisaggregatedAmountsIncludedInFuturePolicyBenefitsAndClaimsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsClaimsDevelopmentTablesDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsClaimsDevelopmentTablesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsReconciliationOfUnpaidClaimsToLiabilityForUnpaidClaimsTableDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsReconciliationOfUnpaidClaimsToLiabilityForUnpaidClaimsTableDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsClaimDurationAndPayoutTableDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsClaimDurationAndPayoutTableDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsDiscountingTableDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsDiscountingTableDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsGrossPremiumsOrAssessmentsAndInterestAccretionDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsGrossPremiumsOrAssessmentsAndInterestAccretionDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsRetirementAndIncomeSolutionsDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsRetirementAndIncomeSolutionsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsPrincipalAssetManagementInternationalPensionDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsPrincipalAssetManagementInternationalPensionDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsBenefitsAndProtectionDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsBenefitsAndProtectionDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsAdditionalLiabilityForCertainBenefitFeaturesDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsAdditionalLiabilityForCertainBenefitFeaturesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsCorporateDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsCorporateDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsExpectedFutureGrossPremiumsAndBenefitPaymentsDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsExpectedFutureGrossPremiumsAndBenefitPaymentsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFuturePolicyBenefitsAndClaimsInterestAccretionAndCurrentDiscountRatesDetails" roleURI="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsInterestAccretionAndCurrentDiscountRatesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureMarketRiskBenefitsAssetAndLiabilityPositionAndReconciliationDetails" roleURI="http://principal.com/role/DisclosureMarketRiskBenefitsAssetAndLiabilityPositionAndReconciliationDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureMarketRiskBenefitsNetAssetLiabilityBalancesAndChangesInValuationOfMrbsForIndividualVariableAnnuitiesDetails" roleURI="http://principal.com/role/DisclosureMarketRiskBenefitsNetAssetLiabilityBalancesAndChangesInValuationOfMrbsForIndividualVariableAnnuitiesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureMarketRiskBenefitsUnobservableInputsForFairValueMeasurementDetails" roleURI="http://principal.com/role/DisclosureMarketRiskBenefitsUnobservableInputsForFairValueMeasurementDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureReinsuranceDetails" roleURI="http://principal.com/role/DisclosureReinsuranceDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureReinsuranceFundsWithheldDetails" roleURI="http://principal.com/role/DisclosureReinsuranceFundsWithheldDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureReinsuranceComponentsOfNetInvestmentIncomeOnFundsWithheldAssetsDetails" roleURI="http://principal.com/role/DisclosureReinsuranceComponentsOfNetInvestmentIncomeOnFundsWithheldAssetsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureReinsuranceComponentsOfNetRealizedCapitalGainsLossesOnFundsWithheldAssetsDetails" roleURI="http://principal.com/role/DisclosureReinsuranceComponentsOfNetRealizedCapitalGainsLossesOnFundsWithheldAssetsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDebtShortTermDebtDetails" roleURI="http://principal.com/role/DisclosureDebtShortTermDebtDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDebtComponentsOfLongTermDebtDetails" roleURI="http://principal.com/role/DisclosureDebtComponentsOfLongTermDebtDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDebtSeniorNotesAndJuniorSubordinatedNotesDetails" roleURI="http://principal.com/role/DisclosureDebtSeniorNotesAndJuniorSubordinatedNotesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDebtNonRecourseMortgagesAndNotesPayableDetails" roleURI="http://principal.com/role/DisclosureDebtNonRecourseMortgagesAndNotesPayableDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureDebtContingentFundingAgreementsDetails" roleURI="http://principal.com/role/DisclosureDebtContingentFundingAgreementsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureIncomeTaxesEffectiveIncomeTaxRateDetails" roleURI="http://principal.com/role/DisclosureIncomeTaxesEffectiveIncomeTaxRateDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureIncomeTaxesDeferredIncomeTaxesAndOtherDetails" roleURI="http://principal.com/role/DisclosureIncomeTaxesDeferredIncomeTaxesAndOtherDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEmployeeAndAgentBenefitsPlanInformationDetails" roleURI="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsPlanInformationDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEmployeeAndAgentBenefitsBenefitObligationAndFundedStatusDetails" roleURI="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsBenefitObligationAndFundedStatusDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEmployeeAndAgentBenefitsAboInExcessOfPlanAssetsDetails" roleURI="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsAboInExcessOfPlanAssetsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEmployeeAndAgentBenefitsNetPeriodicBenefitCostDetails" roleURI="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsNetPeriodicBenefitCostDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEmployeeAndAgentBenefitsWeightedAverageAssumptionsDetails" roleURI="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsWeightedAverageAssumptionsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEmployeeAndAgentBenefitsFairValueOfPlanAssetsDetails" roleURI="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsFairValueOfPlanAssetsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEmployeeAndAgentBenefitsTargetPlanAssetAllocationDetails" roleURI="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsTargetPlanAssetAllocationDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEmployeeAndAgentBenefitsContributionsAndEstimatedFutureBenefitPaymentsDetails" roleURI="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsContributionsAndEstimatedFutureBenefitPaymentsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEmployeeAndAgentBenefitsSupplementalInformationQualifiedAndNonqualifiedPlansDetails" roleURI="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsSupplementalInformationQualifiedAndNonqualifiedPlansDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEmployeeAndAgentBenefitsDefinedContributionAndDeferredCompensationPlansDetails" roleURI="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsDefinedContributionAndDeferredCompensationPlansDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureContingenciesGuaranteesIndemnificationsAndLeasesGuaranteesAndIndemnificationsDetails" roleURI="http://principal.com/role/DisclosureContingenciesGuaranteesIndemnificationsAndLeasesGuaranteesAndIndemnificationsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStockholdersEquityCommonStockDividendsAndReconciliationOfOutstandingCommonSharesDetails" roleURI="http://principal.com/role/DisclosureStockholdersEquityCommonStockDividendsAndReconciliationOfOutstandingCommonSharesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStockholdersEquityOtherComprehensiveIncomeLossDetails" roleURI="http://principal.com/role/DisclosureStockholdersEquityOtherComprehensiveIncomeLossDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStockholdersEquityAociAndNoncontrollingInterestDetails" roleURI="http://principal.com/role/DisclosureStockholdersEquityAociAndNoncontrollingInterestDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStockholdersEquityDividendLimitationsDetails" roleURI="http://principal.com/role/DisclosureStockholdersEquityDividendLimitationsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails" roleURI="http://principal.com/role/DisclosureFairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFairValueMeasurementsChangesInLevel3FairValueMeasurementsDetails" roleURI="http://principal.com/role/DisclosureFairValueMeasurementsChangesInLevel3FairValueMeasurementsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFairValueMeasurementsTransfersDetails" roleURI="http://principal.com/role/DisclosureFairValueMeasurementsTransfersDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFairValueMeasurementsQuantitativeInformationForLevel3MeasurementsDetails" roleURI="http://principal.com/role/DisclosureFairValueMeasurementsQuantitativeInformationForLevel3MeasurementsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFairValueMeasurementsFairValueOptionOnConsolidatedViesDetails" roleURI="http://principal.com/role/DisclosureFairValueMeasurementsFairValueOptionOnConsolidatedViesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureFairValueMeasurementsFinancialInstrumentsNotReportedAtFairValueDetails" roleURI="http://principal.com/role/DisclosureFairValueMeasurementsFinancialInstrumentsNotReportedAtFairValueDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStatutoryInsuranceFinancialInformationDetails" roleURI="http://principal.com/role/DisclosureStatutoryInsuranceFinancialInformationDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSegmentInformationReconciliationOfSegmentAssetsToConsolidatedDetails" roleURI="http://principal.com/role/DisclosureSegmentInformationReconciliationOfSegmentAssetsToConsolidatedDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSegmentInformationReconciliationOfSegmentOperatingRevenuesConsolidatedDetails" roleURI="http://principal.com/role/DisclosureSegmentInformationReconciliationOfSegmentOperatingRevenuesConsolidatedDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSegmentInformationRevenuesFromExitedBusinessDetails" roleURI="http://principal.com/role/DisclosureSegmentInformationRevenuesFromExitedBusinessDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSegmentInformationReconciliationOfSegmentExpensesDetails" roleURI="http://principal.com/role/DisclosureSegmentInformationReconciliationOfSegmentExpensesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSegmentInformationExpensesFromExitedBusinessDetails" roleURI="http://principal.com/role/DisclosureSegmentInformationExpensesFromExitedBusinessDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSegmentInformationSegmentPreTaxOperatingEarningsDetails" roleURI="http://principal.com/role/DisclosureSegmentInformationSegmentPreTaxOperatingEarningsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSegmentInformationPreTaxNetRealizedCapitalGainsLossesDetails" roleURI="http://principal.com/role/DisclosureSegmentInformationPreTaxNetRealizedCapitalGainsLossesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSegmentInformationPreTaxIncomeLossFromExitedBusinessDetails" roleURI="http://principal.com/role/DisclosureSegmentInformationPreTaxIncomeLossFromExitedBusinessDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSegmentInformationIncomeTaxExpenseBenefitBySegmentDetails" roleURI="http://principal.com/role/DisclosureSegmentInformationIncomeTaxExpenseBenefitBySegmentDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSegmentInformationIncomeTaxExpenseBenefitRelatedToExitedBusinessDetails" roleURI="http://principal.com/role/DisclosureSegmentInformationIncomeTaxExpenseBenefitRelatedToExitedBusinessDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureRevenuesFromContractsWithCustomersDisaggregationBySegmentDetails" roleURI="http://principal.com/role/DisclosureRevenuesFromContractsWithCustomersDisaggregationBySegmentDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureRevenuesFromContractsWithCustomersDisaggregationWithinSegmentsDetails" roleURI="http://principal.com/role/DisclosureRevenuesFromContractsWithCustomersDisaggregationWithinSegmentsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStockBasedCompensationPlansStockBasedAwardsDetails" roleURI="http://principal.com/role/DisclosureStockBasedCompensationPlansStockBasedAwardsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStockBasedCompensationPlansNonqualifiedStockOptionsActivityDetails" roleURI="http://principal.com/role/DisclosureStockBasedCompensationPlansNonqualifiedStockOptionsActivityDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStockBasedCompensationPlansNonqualifiedStockOptionsRangeOfExercisePricesDetails" roleURI="http://principal.com/role/DisclosureStockBasedCompensationPlansNonqualifiedStockOptionsRangeOfExercisePricesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStockBasedCompensationPlansNonqualifiedStockOptionsOtherDisclosuresDetails" roleURI="http://principal.com/role/DisclosureStockBasedCompensationPlansNonqualifiedStockOptionsOtherDisclosuresDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStockBasedCompensationPlansPerformanceShareAwardsAndRestrictedStockUnitsDetails" roleURI="http://principal.com/role/DisclosureStockBasedCompensationPlansPerformanceShareAwardsAndRestrictedStockUnitsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStockBasedCompensationPlansEmployeeStockPurchasePlanDetails" roleURI="http://principal.com/role/DisclosureStockBasedCompensationPlansEmployeeStockPurchasePlanDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureEarningsPerCommonShareDetails" roleURI="http://principal.com/role/DisclosureEarningsPerCommonShareDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureSubsequentEventDetails" roleURI="http://principal.com/role/DisclosureSubsequentEventDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureScheduleISummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesDetails" roleURI="http://principal.com/role/DisclosureScheduleISummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfFinancialPositionDetails" roleURI="http://principal.com/role/DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfFinancialPositionDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfFinancialPositionParentheticalDetails" roleURI="http://principal.com/role/DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfFinancialPositionParentheticalDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfOperationsDetails" roleURI="http://principal.com/role/DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfOperationsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfCashFlowsDetails" roleURI="http://principal.com/role/DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfCashFlowsDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyFinancialStatementFootnotesDetails" roleURI="http://principal.com/role/DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyFinancialStatementFootnotesDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureScheduleIiiSupplementaryInsuranceInformationDetails" roleURI="http://principal.com/role/DisclosureScheduleIiiSupplementaryInsuranceInformationDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <roleRef xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureScheduleIvReinsuranceDetails" roleURI="http://principal.com/role/DisclosureScheduleIvReinsuranceDetails" xmlns="http://www.xbrl.org/2003/linkbase" />
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/TradingArrangementsOnly" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#TradingArrangmentsOnly" xlink:type="simple" />
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#IndividualsOnly" xlink:type="simple" />
  <link:roleRef roleURI="http://principal.com/role/DisclosureStandardAndCustomAxisDomainDefaults" xlink:type="simple" xlink:href="pfg-20251231.xsd#DisclosureStandardAndCustomAxisDomainDefaults" />
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-roles-2025.xsd#eedm" />
  <link:arcroleRef arcroleURI="http://www.esma.europa.eu/xbrl/esef/arcrole/wider-narrower" xlink:type="simple" xlink:href="http://www.xbrl.org/lrr/arcrole/esma-arcrole-2018-11-21.xsd#wider-narrower" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" />
  <link:definitionLink xlink:type="extended" xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementAbstract" xlink:label="IncomeStatementAbstract" xlink:title="IncomeStatementAbstract" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" xlink:label="OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" xlink:title="OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncomeStatementAbstract" xlink:to="OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" xlink:title="definition: IncomeStatementAbstract to OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" use="optional" priority="0" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" xlink:label="OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization_2" xlink:title="OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncomeStatementAbstract" xlink:to="OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization_2" xlink:title="definition: IncomeStatementAbstract to OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" use="optional" priority="0" order="6" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BenefitsLossesAndExpenses" xlink:label="BenefitsLossesAndExpenses" xlink:title="BenefitsLossesAndExpenses" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncomeStatementAbstract" xlink:to="BenefitsLossesAndExpenses" xlink:title="definition: IncomeStatementAbstract to BenefitsLossesAndExpenses" use="optional" priority="0" order="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnInvestments" xlink:label="GainLossOnInvestments" xlink:title="GainLossOnInvestments" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncomeStatementAbstract" xlink:to="GainLossOnInvestments" xlink:title="definition: IncomeStatementAbstract to GainLossOnInvestments" use="optional" priority="0" order="3" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GainLossOnFundsWithheldAssets" xlink:label="GainLossOnFundsWithheldAssets" xlink:title="GainLossOnFundsWithheldAssets" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncomeStatementAbstract" xlink:to="GainLossOnFundsWithheldAssets" xlink:title="definition: IncomeStatementAbstract to GainLossOnFundsWithheldAssets" use="optional" priority="0" order="4" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivative" xlink:label="ChangeInFairValueOfFundsWithheldEmbeddedDerivative" xlink:title="ChangeInFairValueOfFundsWithheldEmbeddedDerivative" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncomeStatementAbstract" xlink:to="ChangeInFairValueOfFundsWithheldEmbeddedDerivative" xlink:title="definition: IncomeStatementAbstract to ChangeInFairValueOfFundsWithheldEmbeddedDerivative" use="optional" priority="0" order="5" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOfOtherComprehensiveIncomeAbstract" xlink:label="StatementOfOtherComprehensiveIncomeAbstract" xlink:title="StatementOfOtherComprehensiveIncomeAbstract" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherComprehensiveIncomeAvailableForSaleSecuritiesPeriodIncreaseDecreaseNetOfTax" xlink:label="OtherComprehensiveIncomeAvailableForSaleSecuritiesPeriodIncreaseDecreaseNetOfTax" xlink:title="OtherComprehensiveIncomeAvailableForSaleSecuritiesPeriodIncreaseDecreaseNetOfTax" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="StatementOfOtherComprehensiveIncomeAbstract" xlink:to="OtherComprehensiveIncomeAvailableForSaleSecuritiesPeriodIncreaseDecreaseNetOfTax" xlink:title="definition: StatementOfOtherComprehensiveIncomeAbstract to OtherComprehensiveIncomeAvailableForSaleSecuritiesPeriodIncreaseDecreaseNetOfTax" use="optional" priority="0" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherComprehensiveIncomeDerivativesPeriodIncreaseDecreaseNetOfTax" xlink:label="OtherComprehensiveIncomeDerivativesPeriodIncreaseDecreaseNetOfTax" xlink:title="OtherComprehensiveIncomeDerivativesPeriodIncreaseDecreaseNetOfTax" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="StatementOfOtherComprehensiveIncomeAbstract" xlink:to="OtherComprehensiveIncomeDerivativesPeriodIncreaseDecreaseNetOfTax" xlink:title="definition: StatementOfOtherComprehensiveIncomeAbstract to OtherComprehensiveIncomeDerivativesPeriodIncreaseDecreaseNetOfTax" use="optional" priority="0" order="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract" xlink:label="AssetsAbstract" xlink:title="AssetsAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="PropertyPlantAndEquipmentNet" xlink:title="PropertyPlantAndEquipmentNet" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="AssetsAbstract" xlink:to="PropertyPlantAndEquipmentNet" xlink:title="definition: AssetsAbstract to PropertyPlantAndEquipmentNet" use="optional" priority="0" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:label="PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:title="PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="AssetsAbstract" xlink:to="PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:title="definition: AssetsAbstract to PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" use="optional" priority="0" order="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAbstract" xlink:label="LiabilitiesAbstract" xlink:title="LiabilitiesAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense" xlink:label="LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense" xlink:title="LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="LiabilitiesAbstract" xlink:to="LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense" xlink:title="definition: LiabilitiesAbstract to LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense" use="optional" priority="0" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BenefitsLossesAndExpensesAbstract" xlink:label="BenefitsLossesAndExpensesAbstract" xlink:title="BenefitsLossesAndExpensesAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" xlink:label="PolicyholderBenefitsAndClaimsIncurredNet" xlink:title="PolicyholderBenefitsAndClaimsIncurredNet" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="BenefitsLossesAndExpensesAbstract" xlink:to="PolicyholderBenefitsAndClaimsIncurredNet" xlink:title="definition: BenefitsLossesAndExpensesAbstract to PolicyholderBenefitsAndClaimsIncurredNet" use="optional" priority="0" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" xlink:label="us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" xlink:title="us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" />
    <link:definitionArc xlink:type="arc" xlink:from="IncomeStatementAbstract" xlink:to="us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:IncomeStatementAbstract To us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" order="7" priority="0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" xlink:title="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" />
    <link:definitionArc xlink:type="arc" xlink:from="AssetsAbstract" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:AssetsAbstract To us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" order="3" priority="0" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ContractholderFunds" xlink:label="pfg_ContractholderFunds_2" xlink:title="pfg_ContractholderFunds_2" />
    <link:definitionArc xlink:type="arc" xlink:from="LiabilitiesAbstract" xlink:to="pfg_ContractholderFunds_2" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:LiabilitiesAbstract To pfg_ContractholderFunds_2" order="2" priority="0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_1" xlink:title="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_1" />
    <link:definitionArc xlink:type="arc" xlink:from="LiabilitiesAbstract" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:LiabilitiesAbstract To us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_1" order="3" priority="0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" xlink:label="us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" xlink:title="us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" />
    <link:definitionArc xlink:type="arc" xlink:from="AssetsAbstract" xlink:to="us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:AssetsAbstract To us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" order="4" priority="0" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ContractholderFunds" xlink:label="pfg_ContractholderFunds_3" xlink:title="pfg_ContractholderFunds_3" />
    <link:definitionArc xlink:type="arc" xlink:from="AssetsAbstract" xlink:to="pfg_ContractholderFunds_3" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:AssetsAbstract To pfg_ContractholderFunds_3" order="5" priority="0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="us-gaap_IncomeTaxAuthorityDomain_2" xlink:title="us-gaap_IncomeTaxAuthorityDomain_2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_CA" xlink:label="stpr_CA" xlink:title="stpr_CA" />
    <link:definitionArc xlink:type="arc" xlink:from="us-gaap_IncomeTaxAuthorityDomain_2" xlink:to="stpr_CA" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:us-gaap_IncomeTaxAuthorityDomain_2 To stpr_CA" order="15" priority="0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_IA" xlink:label="stpr_IA_1" xlink:title="stpr_IA_1" />
    <link:definitionArc xlink:type="arc" xlink:from="us-gaap_IncomeTaxAuthorityDomain_2" xlink:to="stpr_IA_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:us-gaap_IncomeTaxAuthorityDomain_2 To stpr_IA_1" order="16" priority="0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_IL" xlink:label="stpr_IL_1" xlink:title="stpr_IL_1" />
    <link:definitionArc xlink:type="arc" xlink:from="us-gaap_IncomeTaxAuthorityDomain_2" xlink:to="stpr_IL_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:us-gaap_IncomeTaxAuthorityDomain_2 To stpr_IL_1" order="17" priority="0" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://principal.com/role/DisclosureStandardAndCustomAxisDomainDefaults">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeAxis" xlink:label="InvestmentTypeAxis" xlink:title="InvestmentTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="InvestmentTypeCategorizationMember" xlink:title="InvestmentTypeCategorizationMember" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="InvestmentTypeAxis" xlink:to="InvestmentTypeCategorizationMember" xlink:title="definition: InvestmentTypeAxis to InvestmentTypeCategorizationMember" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="FinancialInstrumentAxis" xlink:title="FinancialInstrumentAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:title="TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FinancialInstrumentAxis" xlink:to="TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:title="definition: FinancialInstrumentAxis to TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="RetirementPlanTypeAxis" xlink:title="RetirementPlanTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="RetirementPlanTypeDomain" xlink:title="RetirementPlanTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="RetirementPlanTypeAxis" xlink:to="RetirementPlanTypeDomain" xlink:title="definition: RetirementPlanTypeAxis to RetirementPlanTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="RangeAxis" xlink:title="RangeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="RangeMember" xlink:title="RangeMember" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="RangeAxis" xlink:to="RangeMember" xlink:title="definition: RangeAxis to RangeMember" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="IncomeStatementLocationAxis" xlink:title="IncomeStatementLocationAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="IncomeStatementLocationDomain" xlink:title="IncomeStatementLocationDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="IncomeStatementLocationAxis" xlink:to="IncomeStatementLocationDomain" xlink:title="definition: IncomeStatementLocationAxis to IncomeStatementLocationDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTaxStatusAxis" xlink:label="RetirementPlanTaxStatusAxis" xlink:title="RetirementPlanTaxStatusAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTaxStatusDomain" xlink:label="RetirementPlanTaxStatusDomain" xlink:title="RetirementPlanTaxStatusDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="RetirementPlanTaxStatusAxis" xlink:to="RetirementPlanTaxStatusDomain" xlink:title="definition: RetirementPlanTaxStatusAxis to RetirementPlanTaxStatusDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="FairValueByFairValueHierarchyLevelAxis" xlink:title="FairValueByFairValueHierarchyLevelAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="FairValueMeasurementsFairValueHierarchyDomain" xlink:title="FairValueMeasurementsFairValueHierarchyDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FairValueByFairValueHierarchyLevelAxis" xlink:to="FairValueMeasurementsFairValueHierarchyDomain" xlink:title="definition: FairValueByFairValueHierarchyLevelAxis to FairValueMeasurementsFairValueHierarchyDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:label="DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:title="DefinedBenefitPlanByPlanAssetCategoriesAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="PlanAssetCategoriesDomain" xlink:title="PlanAssetCategoriesDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:to="PlanAssetCategoriesDomain" xlink:title="definition: DefinedBenefitPlanByPlanAssetCategoriesAxis to PlanAssetCategoriesDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis" xlink:label="LegalEntityAxis" xlink:title="LegalEntityAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="EntityDomain" xlink:title="EntityDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="LegalEntityAxis" xlink:to="EntityDomain" xlink:title="definition: LegalEntityAxis to EntityDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="StatementBusinessSegmentsAxis" xlink:title="StatementBusinessSegmentsAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="SegmentDomain" xlink:title="SegmentDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="StatementBusinessSegmentsAxis" xlink:to="SegmentDomain" xlink:title="definition: StatementBusinessSegmentsAxis to SegmentDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:label="CumulativeEffectPeriodOfAdoptionAxis" xlink:title="CumulativeEffectPeriodOfAdoptionAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:label="CumulativeEffectPeriodOfAdoptionDomain" xlink:title="CumulativeEffectPeriodOfAdoptionDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="CumulativeEffectPeriodOfAdoptionAxis" xlink:to="CumulativeEffectPeriodOfAdoptionDomain" xlink:title="definition: CumulativeEffectPeriodOfAdoptionAxis to CumulativeEffectPeriodOfAdoptionDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementScenarioAxis" xlink:label="StatementScenarioAxis" xlink:title="StatementScenarioAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="ScenarioUnspecifiedDomain" xlink:title="ScenarioUnspecifiedDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="StatementScenarioAxis" xlink:to="ScenarioUnspecifiedDomain" xlink:title="definition: StatementScenarioAxis to ScenarioUnspecifiedDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="AdjustmentsForNewAccountingPronouncementsAxis" xlink:title="AdjustmentsForNewAccountingPronouncementsAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="TypeOfAdoptionMember" xlink:title="TypeOfAdoptionMember" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="TypeOfAdoptionMember" xlink:title="definition: AdjustmentsForNewAccountingPronouncementsAxis to TypeOfAdoptionMember" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FreshStartAdjustmentsTypeOfFreshStartAdjustmentAxis" xlink:label="FreshStartAdjustmentsTypeOfFreshStartAdjustmentAxis" xlink:title="FreshStartAdjustmentsTypeOfFreshStartAdjustmentAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfFreshStartAdjustmentDomain" xlink:label="TypeOfFreshStartAdjustmentDomain" xlink:title="TypeOfFreshStartAdjustmentDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FreshStartAdjustmentsTypeOfFreshStartAdjustmentAxis" xlink:to="TypeOfFreshStartAdjustmentDomain" xlink:title="definition: FreshStartAdjustmentsTypeOfFreshStartAdjustmentAxis to TypeOfFreshStartAdjustmentDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RestatementAxis" xlink:label="RestatementAxis" xlink:title="RestatementAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RestatementDomain" xlink:label="RestatementDomain" xlink:title="RestatementDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="RestatementAxis" xlink:to="RestatementDomain" xlink:title="definition: RestatementAxis to RestatementDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgedStatusAxis" xlink:label="PledgedStatusAxis" xlink:title="PledgedStatusAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgedStatusDomain" xlink:label="PledgedStatusDomain" xlink:title="PledgedStatusDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="PledgedStatusAxis" xlink:to="PledgedStatusDomain" xlink:title="definition: PledgedStatusAxis to PledgedStatusDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgingPurposeAxis" xlink:label="PledgingPurposeAxis" xlink:title="PledgingPurposeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgingPurposeDomain" xlink:label="PledgingPurposeDomain" xlink:title="PledgingPurposeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="PledgingPurposeAxis" xlink:to="PledgingPurposeDomain" xlink:title="definition: PledgingPurposeAxis to PledgingPurposeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="ConsolidationItemsAxis" xlink:title="ConsolidationItemsAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="ConsolidationItemsDomain" xlink:title="ConsolidationItemsDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ConsolidationItemsAxis" xlink:to="ConsolidationItemsDomain" xlink:title="definition: ConsolidationItemsAxis to ConsolidationItemsDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis" xlink:label="ConsolidatedEntitiesAxis" xlink:title="ConsolidatedEntitiesAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="ConsolidatedEntitiesDomain" xlink:title="ConsolidatedEntitiesDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ConsolidatedEntitiesAxis" xlink:to="ConsolidatedEntitiesDomain" xlink:title="definition: ConsolidatedEntitiesAxis to ConsolidatedEntitiesDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="StatementEquityComponentsAxis" xlink:title="StatementEquityComponentsAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain" xlink:label="EquityComponentDomain" xlink:title="EquityComponentDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="StatementEquityComponentsAxis" xlink:to="EquityComponentDomain" xlink:title="definition: StatementEquityComponentsAxis to EquityComponentDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="StatementEquityComponentsAxis_2" xlink:title="StatementEquityComponentsAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain" xlink:label="EquityComponentDomain_2" xlink:title="EquityComponentDomain" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="ProductOrServiceAxis" xlink:title="ProductOrServiceAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="ProductsAndServicesDomain" xlink:title="ProductsAndServicesDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ProductOrServiceAxis" xlink:to="ProductsAndServicesDomain" xlink:title="definition: ProductOrServiceAxis to ProductsAndServicesDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis" xlink:label="AwardTypeAxis" xlink:title="AwardTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="AwardTypeAxis" xlink:to="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="definition: AwardTypeAxis to ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationTypeAxis" xlink:label="ReclassificationTypeAxis" xlink:title="ReclassificationTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationTypeDomain" xlink:label="ReclassificationTypeDomain" xlink:title="ReclassificationTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ReclassificationTypeAxis" xlink:to="ReclassificationTypeDomain" xlink:title="definition: ReclassificationTypeAxis to ReclassificationTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsByNatureAxis" xlink:label="GuaranteeObligationsByNatureAxis" xlink:title="GuaranteeObligationsByNatureAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsNatureDomain" xlink:label="GuaranteeObligationsNatureDomain" xlink:title="GuaranteeObligationsNatureDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="GuaranteeObligationsByNatureAxis" xlink:to="GuaranteeObligationsNatureDomain" xlink:title="definition: GuaranteeObligationsByNatureAxis to GuaranteeObligationsNatureDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseAxis" xlink:label="LitigationCaseAxis" xlink:title="LitigationCaseAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain" xlink:label="LitigationCaseTypeDomain" xlink:title="LitigationCaseTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="LitigationCaseAxis" xlink:to="LitigationCaseTypeDomain" xlink:title="definition: LitigationCaseAxis to LitigationCaseTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusAxis" xlink:label="LitigationStatusAxis" xlink:title="LitigationStatusAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain" xlink:label="LitigationStatusDomain" xlink:title="LitigationStatusDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="LitigationStatusAxis" xlink:to="LitigationStatusDomain" xlink:title="definition: LitigationStatusAxis to LitigationStatusDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreementAxis" xlink:label="FundingAgreementAxis" xlink:title="FundingAgreementAxis" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreementDomain" xlink:label="FundingAgreementDomain" xlink:title="FundingAgreementDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FundingAgreementAxis" xlink:to="FundingAgreementDomain" xlink:title="definition: FundingAgreementAxis to FundingAgreementDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis" xlink:label="DebtInstrumentAxis" xlink:title="DebtInstrumentAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="DebtInstrumentNameDomain" xlink:title="DebtInstrumentNameDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="DebtInstrumentAxis" xlink:to="DebtInstrumentNameDomain" xlink:title="definition: DebtInstrumentAxis to DebtInstrumentNameDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis" xlink:label="CounterpartyNameAxis" xlink:title="CounterpartyNameAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="RepurchaseAgreementCounterpartyNameDomain" xlink:title="RepurchaseAgreementCounterpartyNameDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="CounterpartyNameAxis" xlink:to="RepurchaseAgreementCounterpartyNameDomain" xlink:title="definition: CounterpartyNameAxis to RepurchaseAgreementCounterpartyNameDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RecourseStatusAxis" xlink:label="RecourseStatusAxis" xlink:title="RecourseStatusAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RecourseStatusDomain" xlink:label="RecourseStatusDomain" xlink:title="RecourseStatusDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="RecourseStatusAxis" xlink:to="RecourseStatusDomain" xlink:title="definition: RecourseStatusAxis to RecourseStatusDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="LongtermDebtTypeAxis" xlink:title="LongtermDebtTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="LongtermDebtTypeDomain" xlink:title="LongtermDebtTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="LongtermDebtTypeAxis" xlink:to="LongtermDebtTypeDomain" xlink:title="definition: LongtermDebtTypeAxis to LongtermDebtTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AirlineDestinationsAxis" xlink:label="AirlineDestinationsAxis_2" xlink:title="AirlineDestinationsAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AirlineDestinationDomain" xlink:label="AirlineDestinationDomain_2" xlink:title="AirlineDestinationDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="AirlineDestinationsAxis_2" xlink:to="AirlineDestinationDomain_2" xlink:title="definition: AirlineDestinationsAxis to AirlineDestinationDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteedInsuranceContractTypeOfBenefitAxis" xlink:label="GuaranteedInsuranceContractTypeOfBenefitAxis" xlink:title="GuaranteedInsuranceContractTypeOfBenefitAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteedInsuranceContractTypeOfBenefitDomain" xlink:label="GuaranteedInsuranceContractTypeOfBenefitDomain" xlink:title="GuaranteedInsuranceContractTypeOfBenefitDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="GuaranteedInsuranceContractTypeOfBenefitAxis" xlink:to="GuaranteedInsuranceContractTypeOfBenefitDomain" xlink:title="definition: GuaranteedInsuranceContractTypeOfBenefitAxis to GuaranteedInsuranceContractTypeOfBenefitDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GuaranteedInsuranceContractMinimumCreditRateRageAxis" xlink:label="GuaranteedInsuranceContractMinimumCreditRateRageAxis" xlink:title="GuaranteedInsuranceContractMinimumCreditRateRageAxis" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GuaranteedInsuranceContractMinimumCreditRateRageDomain" xlink:label="GuaranteedInsuranceContractMinimumCreditRateRageDomain" xlink:title="GuaranteedInsuranceContractMinimumCreditRateRageDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="GuaranteedInsuranceContractMinimumCreditRateRageAxis" xlink:to="GuaranteedInsuranceContractMinimumCreditRateRageDomain" xlink:title="definition: GuaranteedInsuranceContractMinimumCreditRateRageAxis to GuaranteedInsuranceContractMinimumCreditRateRageDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ParentAndSubsidiariesShelfRegistrationDebtGuarantorAxis" xlink:label="ParentAndSubsidiariesShelfRegistrationDebtGuarantorAxis" xlink:title="ParentAndSubsidiariesShelfRegistrationDebtGuarantorAxis" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EntityShelfRegistrationDebtGuarantorDomain" xlink:label="EntityShelfRegistrationDebtGuarantorDomain" xlink:title="EntityShelfRegistrationDebtGuarantorDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ParentAndSubsidiariesShelfRegistrationDebtGuarantorAxis" xlink:to="EntityShelfRegistrationDebtGuarantorDomain" xlink:title="definition: ParentAndSubsidiariesShelfRegistrationDebtGuarantorAxis to EntityShelfRegistrationDebtGuarantorDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="RelatedPartyTransactionsByRelatedPartyAxis" xlink:title="RelatedPartyTransactionsByRelatedPartyAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDomain" xlink:label="RelatedPartyDomain" xlink:title="RelatedPartyDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="RelatedPartyDomain" xlink:title="definition: RelatedPartyTransactionsByRelatedPartyAxis to RelatedPartyDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="IncomeTaxAuthorityAxis" xlink:title="IncomeTaxAuthorityAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="IncomeTaxAuthorityDomain" xlink:title="IncomeTaxAuthorityDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="IncomeTaxAuthorityAxis" xlink:to="IncomeTaxAuthorityDomain" xlink:title="definition: IncomeTaxAuthorityAxis to IncomeTaxAuthorityDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="SubsequentEventTypeAxis" xlink:title="SubsequentEventTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="SubsequentEventTypeDomain" xlink:title="SubsequentEventTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="SubsequentEventTypeAxis" xlink:to="SubsequentEventTypeDomain" xlink:title="definition: SubsequentEventTypeAxis to SubsequentEventTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="BusinessAcquisitionAxis" xlink:title="BusinessAcquisitionAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="BusinessAcquisitionAcquireeDomain" xlink:title="BusinessAcquisitionAcquireeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="BusinessAcquisitionAxis" xlink:to="BusinessAcquisitionAcquireeDomain" xlink:title="definition: BusinessAcquisitionAxis to BusinessAcquisitionAcquireeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="BalanceSheetLocationAxis" xlink:title="BalanceSheetLocationAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="BalanceSheetLocationDomain" xlink:title="BalanceSheetLocationDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="BalanceSheetLocationAxis" xlink:to="BalanceSheetLocationDomain" xlink:title="definition: BalanceSheetLocationAxis to BalanceSheetLocationDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostAxis" xlink:label="CapitalizedContractCostAxis" xlink:title="CapitalizedContractCostAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostDomain" xlink:label="CapitalizedContractCostDomain" xlink:title="CapitalizedContractCostDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="CapitalizedContractCostAxis" xlink:to="CapitalizedContractCostDomain" xlink:title="definition: CapitalizedContractCostAxis to CapitalizedContractCostDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="SubsegmentsAxis" xlink:title="SubsegmentsAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="SubsegmentsDomain" xlink:title="SubsegmentsDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="SubsegmentsAxis" xlink:to="SubsegmentsDomain" xlink:title="definition: SubsegmentsAxis to SubsegmentsDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis" xlink:label="StatementGeographicalAxis" xlink:title="StatementGeographicalAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="SegmentGeographicalDomain" xlink:title="SegmentGeographicalDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="StatementGeographicalAxis" xlink:to="SegmentGeographicalDomain" xlink:title="definition: StatementGeographicalAxis to SegmentGeographicalDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ShareRepurchaseProgramAxis" xlink:label="srt_ShareRepurchaseProgramAxis" xlink:title="ShareRepurchaseProgramAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ShareRepurchaseProgramDomain" xlink:label="srt_ShareRepurchaseProgramDomain" xlink:title="ShareRepurchaseProgramDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_ShareRepurchaseProgramAxis" xlink:to="srt_ShareRepurchaseProgramDomain" xlink:title="definition: ShareRepurchaseProgramAxis to ShareRepurchaseProgramDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsAccidentYearAxis" xlink:label="ShortdurationInsuranceContractsAccidentYearAxis" xlink:title="ShortdurationInsuranceContractsAccidentYearAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:label="ShortdurationInsuranceContractsAccidentYearDomain" xlink:title="ShortdurationInsuranceContractsAccidentYearDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ShortdurationInsuranceContractsAccidentYearAxis" xlink:to="ShortdurationInsuranceContractsAccidentYearDomain" xlink:title="definition: ShortdurationInsuranceContractsAccidentYearAxis to ShortdurationInsuranceContractsAccidentYearDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis" xlink:label="PlanNameAxis" xlink:title="PlanNameAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain" xlink:label="PlanNameDomain" xlink:title="PlanNameDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="PlanNameAxis" xlink:to="PlanNameDomain" xlink:title="definition: PlanNameAxis to PlanNameDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:title="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:title="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:to="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:title="definition: ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis to ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ParentAndSubsidiariesNotesGuarantorAxis" xlink:label="ParentAndSubsidiariesNotesGuarantorAxis" xlink:title="ParentAndSubsidiariesNotesGuarantorAxis" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EntityParentAndSubsidiariesNotesGuarantorDomain" xlink:label="EntityParentAndSubsidiariesNotesGuarantorDomain" xlink:title="EntityParentAndSubsidiariesNotesGuarantorDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ParentAndSubsidiariesNotesGuarantorAxis" xlink:to="EntityParentAndSubsidiariesNotesGuarantorDomain" xlink:title="definition: ParentAndSubsidiariesNotesGuarantorAxis to EntityParentAndSubsidiariesNotesGuarantorDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedContributionPlanParticipantTypeAxis" xlink:label="DefinedContributionPlanParticipantTypeAxis" xlink:title="DefinedContributionPlanParticipantTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedContributionPlanParticipantTypeDomain" xlink:label="DefinedContributionPlanParticipantTypeDomain" xlink:title="DefinedContributionPlanParticipantTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="DefinedContributionPlanParticipantTypeAxis" xlink:to="DefinedContributionPlanParticipantTypeDomain" xlink:title="definition: DefinedContributionPlanParticipantTypeAxis to DefinedContributionPlanParticipantTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:label="FinancingReceivablePortfolioSegmentAxis" xlink:title="FinancingReceivablePortfolioSegmentAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:label="FinancingReceivablePortfolioSegmentDomain" xlink:title="FinancingReceivablePortfolioSegmentDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FinancingReceivablePortfolioSegmentAxis" xlink:to="FinancingReceivablePortfolioSegmentDomain" xlink:title="definition: FinancingReceivablePortfolioSegmentAxis to FinancingReceivablePortfolioSegmentDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis" xlink:label="MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis" xlink:title="MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:label="MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:title="MortgageLoansOnRealEstateNamePropertyTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis" xlink:to="MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:title="definition: MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis to MortgageLoansOnRealEstateNamePropertyTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:title="FiniteLivedIntangibleAssetsByMajorClassAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:title="FiniteLivedIntangibleAssetsMajorClassNameDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:title="definition: FiniteLivedIntangibleAssetsByMajorClassAxis to FiniteLivedIntangibleAssetsMajorClassNameDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:title="IndefiniteLivedIntangibleAssetsByMajorClassAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:title="IndefiniteLivedIntangibleAssetsMajorClassNameDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:title="definition: IndefiniteLivedIntangibleAssetsByMajorClassAxis to IndefiniteLivedIntangibleAssetsMajorClassNameDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="FairValueByMeasurementFrequencyAxis" xlink:title="FairValueByMeasurementFrequencyAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="FairValueMeasurementFrequencyDomain" xlink:title="FairValueMeasurementFrequencyDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FairValueByMeasurementFrequencyAxis" xlink:to="FairValueMeasurementFrequencyDomain" xlink:title="definition: FairValueByMeasurementFrequencyAxis to FairValueMeasurementFrequencyDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="FairValueByAssetClassAxis" xlink:title="FairValueByAssetClassAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:title="FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FairValueByAssetClassAxis" xlink:to="FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:title="definition: FairValueByAssetClassAxis to FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NonrecurringFairValueMeasurementAssetsLiabilitiesAxis" xlink:label="NonrecurringFairValueMeasurementAssetsLiabilitiesAxis" xlink:title="NonrecurringFairValueMeasurementAssetsLiabilitiesAxis" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NonrecurringFairValueMeasurementsAssetsLiabilitiesDomain" xlink:label="NonrecurringFairValueMeasurementsAssetsLiabilitiesDomain" xlink:title="NonrecurringFairValueMeasurementsAssetsLiabilitiesDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="NonrecurringFairValueMeasurementAssetsLiabilitiesAxis" xlink:to="NonrecurringFairValueMeasurementsAssetsLiabilitiesDomain" xlink:title="definition: NonrecurringFairValueMeasurementAssetsLiabilitiesAxis to NonrecurringFairValueMeasurementsAssetsLiabilitiesDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeAxis" xlink:label="MeasurementInputTypeAxis" xlink:title="MeasurementInputTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="MeasurementInputTypeDomain" xlink:title="MeasurementInputTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="MeasurementInputTypeAxis" xlink:to="MeasurementInputTypeDomain" xlink:title="definition: MeasurementInputTypeAxis to MeasurementInputTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" xlink:label="EquityMethodInvestmentNonconsolidatedInvesteeAxis" xlink:title="EquityMethodInvestmentNonconsolidatedInvesteeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" xlink:label="EquityMethodInvestmentNonconsolidatedInvesteeDomain" xlink:title="EquityMethodInvestmentNonconsolidatedInvesteeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="EquityMethodInvestmentNonconsolidatedInvesteeAxis" xlink:to="EquityMethodInvestmentNonconsolidatedInvesteeDomain" xlink:title="definition: EquityMethodInvestmentNonconsolidatedInvesteeAxis to EquityMethodInvestmentNonconsolidatedInvesteeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:title="ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="EquityMethodInvesteeNameDomain" xlink:title="EquityMethodInvesteeNameDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="EquityMethodInvesteeNameDomain" xlink:title="definition: ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis to EquityMethodInvesteeNameDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="FairValueByLiabilityClassAxis" xlink:title="FairValueByLiabilityClassAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:title="FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FairValueByLiabilityClassAxis" xlink:to="FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:title="definition: FairValueByLiabilityClassAxis to FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ValuationTechniqueAxis" xlink:label="ValuationTechniqueAxis" xlink:title="ValuationTechniqueAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="ValuationTechniqueDomain" xlink:title="ValuationTechniqueDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ValuationTechniqueAxis" xlink:to="ValuationTechniqueDomain" xlink:title="definition: ValuationTechniqueAxis to ValuationTechniqueDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditDerivativesByContractTypeAxis" xlink:label="CreditDerivativesByContractTypeAxis" xlink:title="CreditDerivativesByContractTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditDerivativesContractTypeDomain" xlink:label="CreditDerivativesContractTypeDomain" xlink:title="CreditDerivativesContractTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="CreditDerivativesByContractTypeAxis" xlink:to="CreditDerivativesContractTypeDomain" xlink:title="definition: CreditDerivativesByContractTypeAxis to CreditDerivativesContractTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnderlyingAssetClassAxis" xlink:label="UnderlyingAssetClassAxis" xlink:title="UnderlyingAssetClassAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnderlyingAssetClassDomain" xlink:label="UnderlyingAssetClassDomain" xlink:title="UnderlyingAssetClassDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="UnderlyingAssetClassAxis" xlink:to="UnderlyingAssetClassDomain" xlink:title="definition: UnderlyingAssetClassAxis to UnderlyingAssetClassDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CreditRatingStandardPoorsAxis" xlink:label="CreditRatingStandardPoorsAxis" xlink:title="CreditRatingStandardPoorsAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ExternalCreditRatingStandardPoorsMember" xlink:label="ExternalCreditRatingStandardPoorsMember" xlink:title="ExternalCreditRatingStandardPoorsMember" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="CreditRatingStandardPoorsAxis" xlink:to="ExternalCreditRatingStandardPoorsMember" xlink:title="definition: CreditRatingStandardPoorsAxis to ExternalCreditRatingStandardPoorsMember" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablesPeriodPastDueAxis" xlink:label="FinancingReceivablesPeriodPastDueAxis" xlink:title="FinancingReceivablesPeriodPastDueAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain" xlink:label="FinancingReceivablesPeriodPastDueDomain" xlink:title="FinancingReceivablesPeriodPastDueDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FinancingReceivablesPeriodPastDueAxis" xlink:to="FinancingReceivablesPeriodPastDueDomain" xlink:title="definition: FinancingReceivablesPeriodPastDueAxis to FinancingReceivablesPeriodPastDueDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentPerformanceStatusAxis" xlink:label="FinancialInstrumentPerformanceStatusAxis" xlink:title="FinancialInstrumentPerformanceStatusAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentPerformanceStatusDomain" xlink:label="FinancialInstrumentPerformanceStatusDomain" xlink:title="FinancialInstrumentPerformanceStatusDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FinancialInstrumentPerformanceStatusAxis" xlink:to="FinancialInstrumentPerformanceStatusDomain" xlink:title="definition: FinancialInstrumentPerformanceStatusAxis to FinancialInstrumentPerformanceStatusDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MortgageLoansOnRealEstateLoanTypeAxis" xlink:label="MortgageLoansOnRealEstateLoanTypeAxis" xlink:title="MortgageLoansOnRealEstateLoanTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MortgageLoansOnRealEstateLoanTypeDomain" xlink:label="MortgageLoansOnRealEstateLoanTypeDomain" xlink:title="MortgageLoansOnRealEstateLoanTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="MortgageLoansOnRealEstateLoanTypeAxis" xlink:to="MortgageLoansOnRealEstateLoanTypeDomain" xlink:title="definition: MortgageLoansOnRealEstateLoanTypeAxis to MortgageLoansOnRealEstateLoanTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LoanRestructuringModificationAxis" xlink:label="LoanRestructuringModificationAxis" xlink:title="LoanRestructuringModificationAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LoanRestructuringModificationDomain" xlink:label="LoanRestructuringModificationDomain" xlink:title="LoanRestructuringModificationDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="LoanRestructuringModificationAxis" xlink:to="LoanRestructuringModificationDomain" xlink:title="definition: LoanRestructuringModificationAxis to LoanRestructuringModificationDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialAssetTypeAxis" xlink:label="FinancialAssetTypeAxis" xlink:title="FinancialAssetTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialAssetTypeCategorizationDomain" xlink:label="FinancialAssetTypeCategorizationDomain" xlink:title="FinancialAssetTypeCategorizationDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FinancialAssetTypeAxis" xlink:to="FinancialAssetTypeCategorizationDomain" xlink:title="definition: FinancialAssetTypeAxis to FinancialAssetTypeCategorizationDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialLiabilityTypeAxis" xlink:label="FinancialLiabilityTypeAxis" xlink:title="FinancialLiabilityTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialLiabilityTypeCategorizationDomain" xlink:label="FinancialLiabilityTypeCategorizationDomain" xlink:title="FinancialLiabilityTypeCategorizationDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FinancialLiabilityTypeAxis" xlink:to="FinancialLiabilityTypeCategorizationDomain" xlink:title="definition: FinancialLiabilityTypeAxis to FinancialLiabilityTypeCategorizationDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="DerivativeInstrumentRiskAxis" xlink:title="DerivativeInstrumentRiskAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="DerivativeContractTypeDomain" xlink:title="DerivativeContractTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="DerivativeInstrumentRiskAxis" xlink:to="DerivativeContractTypeDomain" xlink:title="definition: DerivativeInstrumentRiskAxis to DerivativeContractTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis" xlink:label="HedgingDesignationAxis" xlink:title="HedgingDesignationAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain" xlink:label="HedgingDesignationDomain" xlink:title="HedgingDesignationDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="HedgingDesignationAxis" xlink:to="HedgingDesignationDomain" xlink:title="definition: HedgingDesignationAxis to HedgingDesignationDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:title="DerivativeInstrumentsGainLossByHedgingRelationshipAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="HedgingRelationshipDomain" xlink:title="HedgingRelationshipDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:to="HedgingRelationshipDomain" xlink:title="definition: DerivativeInstrumentsGainLossByHedgingRelationshipAxis to HedgingRelationshipDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" xlink:label="ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" xlink:title="ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:label="ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:title="ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" xlink:to="ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:title="definition: ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis to ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransactionTypeAxis" xlink:label="TransactionTypeAxis" xlink:title="TransactionTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransactionDomain" xlink:label="TransactionDomain" xlink:title="TransactionDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="TransactionTypeAxis" xlink:to="TransactionDomain" xlink:title="definition: TransactionTypeAxis to TransactionDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="ShortTermDebtTypeAxis" xlink:title="ShortTermDebtTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="ShortTermDebtTypeDomain" xlink:title="ShortTermDebtTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ShortTermDebtTypeAxis" xlink:to="ShortTermDebtTypeDomain" xlink:title="definition: ShortTermDebtTypeAxis to ShortTermDebtTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementBasisAxis" xlink:label="FairValueByMeasurementBasisAxis" xlink:title="FairValueByMeasurementBasisAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:label="PortionAtFairValueFairValueDisclosureMember" xlink:title="PortionAtFairValueFairValueDisclosureMember" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FairValueByMeasurementBasisAxis" xlink:to="PortionAtFairValueFairValueDisclosureMember" xlink:title="definition: FairValueByMeasurementBasisAxis to PortionAtFairValueFairValueDisclosureMember" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:label="FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:title="FundsHeldUnderReinsuranceAgreementsAssetAxis" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:label="FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:title="FundsHeldUnderReinsuranceAgreementsAssetDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:to="FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:title="definition: FundsHeldUnderReinsuranceAgreementsAssetAxis to FundsHeldUnderReinsuranceAgreementsAssetDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="ConcentrationRiskByTypeAxis" xlink:title="ConcentrationRiskByTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="ConcentrationRiskTypeDomain" xlink:title="ConcentrationRiskTypeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ConcentrationRiskByTypeAxis" xlink:to="ConcentrationRiskTypeDomain" xlink:title="definition: ConcentrationRiskByTypeAxis to ConcentrationRiskTypeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededCreditRiskAxis" xlink:label="CededCreditRiskAxis" xlink:title="CededCreditRiskAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededCreditRiskReinsurerDomain" xlink:label="CededCreditRiskReinsurerDomain" xlink:title="CededCreditRiskReinsurerDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="CededCreditRiskAxis" xlink:to="CededCreditRiskReinsurerDomain" xlink:title="definition: CededCreditRiskAxis to CededCreditRiskReinsurerDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="ConcentrationRiskByBenchmarkAxis" xlink:title="ConcentrationRiskByBenchmarkAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="ConcentrationRiskBenchmarkDomain" xlink:title="ConcentrationRiskBenchmarkDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="ConcentrationRiskByBenchmarkAxis" xlink:to="ConcentrationRiskBenchmarkDomain" xlink:title="definition: ConcentrationRiskByBenchmarkAxis to ConcentrationRiskBenchmarkDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountAssetCategoryAxis" xlink:label="SeparateAccountAssetCategoryAxis" xlink:title="SeparateAccountAssetCategoryAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountAssetCategoryDomain" xlink:label="SeparateAccountAssetCategoryDomain" xlink:title="SeparateAccountAssetCategoryDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="SeparateAccountAssetCategoryAxis" xlink:to="SeparateAccountAssetCategoryDomain" xlink:title="definition: SeparateAccountAssetCategoryAxis to SeparateAccountAssetCategoryDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsConsolidationItemsAxis" xlink:label="SubsegmentsConsolidationItemsAxis" xlink:title="SubsegmentsConsolidationItemsAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsConsolidationItemsDomain" xlink:label="SubsegmentsConsolidationItemsDomain" xlink:title="SubsegmentsConsolidationItemsDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="SubsegmentsConsolidationItemsAxis" xlink:to="SubsegmentsConsolidationItemsDomain" xlink:title="definition: SubsegmentsConsolidationItemsAxis to SubsegmentsConsolidationItemsDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis" xlink:label="PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis" xlink:title="PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" xlink:label="PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" xlink:title="PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis" xlink:to="PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" xlink:title="definition: PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis to PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis" xlink:label="PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis" xlink:title="PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" xlink:label="PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" xlink:title="PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis" xlink:to="PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" xlink:title="definition: PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis to PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="TypeOfArrangementAxis" xlink:title="TypeOfArrangementAxis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="ArrangementsAndNonarrangementTransactionsMember" xlink:title="ArrangementsAndNonarrangementTransactionsMember" />
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="TypeOfArrangementAxis" xlink:to="ArrangementsAndNonarrangementTransactionsMember" xlink:title="definition: TypeOfArrangementAxis to ArrangementsAndNonarrangementTransactionsMember" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanAxis" xlink:label="pfg_DefinedBenefitPlanAxis_1" xlink:title="pfg_DefinedBenefitPlanAxis_1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanNameDomain" xlink:label="pfg_DefinedBenefitPlanNameDomain_1" xlink:title="pfg_DefinedBenefitPlanNameDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="pfg_DefinedBenefitPlanAxis_1" xlink:to="pfg_DefinedBenefitPlanNameDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:pfg_DefinedBenefitPlanAxis_1 To pfg_DefinedBenefitPlanNameDomain_1" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialPositionAxis" xlink:label="pfg_FinancialPositionAxis_1" xlink:title="pfg_FinancialPositionAxis_1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialPositionDomain" xlink:label="pfg_FinancialPositionDomain_1" xlink:title="pfg_FinancialPositionDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="pfg_FinancialPositionAxis_1" xlink:to="pfg_FinancialPositionDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:pfg_FinancialPositionAxis_1 To pfg_FinancialPositionDomain_1" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis" xlink:label="us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_1" xlink:title="us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain" xlink:label="us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_1" xlink:title="us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_1" xlink:to="us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_1 To us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_1" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOfFinancialPositionLocationActivityCapitalizationAxis" xlink:label="us-gaap_StatementOfFinancialPositionLocationActivityCapitalizationAxis_1" xlink:title="us-gaap_StatementOfFinancialPositionLocationActivityCapitalizationAxis_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOfFinancialPositionLocationActivityCapitalizationDomain" xlink:label="us-gaap_StatementOfFinancialPositionLocationActivityCapitalizationDomain_1" xlink:title="us-gaap_StatementOfFinancialPositionLocationActivityCapitalizationDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="us-gaap_StatementOfFinancialPositionLocationActivityCapitalizationAxis_1" xlink:to="us-gaap_StatementOfFinancialPositionLocationActivityCapitalizationDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:us-gaap_StatementOfFinancialPositionLocationActivityCapitalizationAxis_1 To us-gaap_StatementOfFinancialPositionLocationActivityCapitalizationDomain_1" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOfFinancialPositionLocationActivityAccrualAxis" xlink:label="us-gaap_StatementOfFinancialPositionLocationActivityAccrualAxis_1" xlink:title="us-gaap_StatementOfFinancialPositionLocationActivityAccrualAxis_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOfFinancialPositionLocationActivityAccrualDomain" xlink:label="us-gaap_StatementOfFinancialPositionLocationActivityAccrualDomain_1" xlink:title="us-gaap_StatementOfFinancialPositionLocationActivityAccrualDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="us-gaap_StatementOfFinancialPositionLocationActivityAccrualAxis_1" xlink:to="us-gaap_StatementOfFinancialPositionLocationActivityAccrualDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:us-gaap_StatementOfFinancialPositionLocationActivityAccrualAxis_1 To us-gaap_StatementOfFinancialPositionLocationActivityAccrualDomain_1" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxCreditCarryforwardAxis" xlink:label="us-gaap_TaxCreditCarryforwardAxis_1" xlink:title="us-gaap_TaxCreditCarryforwardAxis_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxCreditCarryforwardNameDomain" xlink:label="us-gaap_TaxCreditCarryforwardNameDomain_1" xlink:title="us-gaap_TaxCreditCarryforwardNameDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="us-gaap_TaxCreditCarryforwardAxis_1" xlink:to="us-gaap_TaxCreditCarryforwardNameDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:us-gaap_TaxCreditCarryforwardAxis_1 To us-gaap_TaxCreditCarryforwardNameDomain_1" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeInstrumentContractAxis" xlink:label="pfg_DerivativeInstrumentContractAxis_1" xlink:title="pfg_DerivativeInstrumentContractAxis_1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeInstrumentContractDomain" xlink:label="pfg_DerivativeInstrumentContractDomain_1" xlink:title="pfg_DerivativeInstrumentContractDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="pfg_DerivativeInstrumentContractAxis_1" xlink:to="pfg_DerivativeInstrumentContractDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:pfg_DerivativeInstrumentContractAxis_1 To pfg_DerivativeInstrumentContractDomain_1" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis_1" xlink:title="us-gaap_StatementClassOfStockAxis_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain_1" xlink:title="us-gaap_ClassOfStockDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="us-gaap_StatementClassOfStockAxis_1" xlink:to="us-gaap_ClassOfStockDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:us-gaap_StatementClassOfStockAxis_1 To us-gaap_ClassOfStockDomain_1" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_1" xlink:title="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1" xlink:title="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_1" xlink:to="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_1 To us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis" xlink:label="us-gaap_DisposalGroupClassificationAxis_1" xlink:title="us-gaap_DisposalGroupClassificationAxis_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain" xlink:label="us-gaap_DisposalGroupClassificationDomain_1" xlink:title="us-gaap_DisposalGroupClassificationDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="us-gaap_DisposalGroupClassificationAxis_1" xlink:to="us-gaap_DisposalGroupClassificationDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:us-gaap_DisposalGroupClassificationAxis_1 To us-gaap_DisposalGroupClassificationDomain_1" order="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PartnerCapitalComponentsAxis" xlink:label="us-gaap_PartnerCapitalComponentsAxis_1" xlink:title="us-gaap_PartnerCapitalComponentsAxis_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PartnerCapitalComponentsDomain" xlink:label="us-gaap_PartnerCapitalComponentsDomain_1" xlink:title="us-gaap_PartnerCapitalComponentsDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="us-gaap_PartnerCapitalComponentsAxis_1" xlink:to="us-gaap_PartnerCapitalComponentsDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:us-gaap_PartnerCapitalComponentsAxis_1 To us-gaap_PartnerCapitalComponentsDomain_1" order="1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_RetirementPlanParticipantsEntryByDateAxis" xlink:label="pfg_RetirementPlanParticipantsEntryByDateAxis_1" xlink:title="pfg_RetirementPlanParticipantsEntryByDateAxis_1" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_RetirementPlanParticipantsEntryByDateDomain" xlink:label="pfg_RetirementPlanParticipantsEntryByDateDomain_1" xlink:title="pfg_RetirementPlanParticipantsEntryByDateDomain_1" />
    <link:definitionArc xlink:type="arc" xlink:from="pfg_RetirementPlanParticipantsEntryByDateAxis_1" xlink:to="pfg_RetirementPlanParticipantsEntryByDateDomain_1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:title="definition:pfg_RetirementPlanParticipantsEntryByDateAxis_1 To pfg_RetirementPlanParticipantsEntryByDateDomain_1" order="1" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended" xlink:title="Individuals">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#ecd_AllIndividualsMember" xlink:label="ecd_AllIndividualsMember" xlink:title="ecd_AllIndividualsMember" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_KennethMccullumMember" xlink:label="pfg_KennethMccullumMember" xlink:title="pfg_KennethMccullumMember" />
    <link:definitionArc xlink:type="arc" xlink:from="ecd_AllIndividualsMember" xlink:to="pfg_KennethMccullumMember" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:ecd_AllIndividualsMember To pfg_KennethMccullumMember" order="1" priority="0" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_KamalBhatiaMember" xlink:label="pfg_KamalBhatiaMember" xlink:title="pfg_KamalBhatiaMember" />
    <link:definitionArc xlink:type="arc" xlink:from="ecd_AllIndividualsMember" xlink:to="pfg_KamalBhatiaMember" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:ecd_AllIndividualsMember To pfg_KamalBhatiaMember" order="2" priority="0" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/TradingArrangementsOnly" xlink:type="extended" xlink:title="Trading Arrangements">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#ecd_AllTradingArrangementsMember" xlink:label="ecd_AllTradingArrangementsMember" xlink:title="ecd_AllTradingArrangementsMember" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CommonStockUnderlyingStockOptionsToExtentExercisedForSharePurchasesMember" xlink:label="pfg_CommonStockUnderlyingStockOptionsToExtentExercisedForSharePurchasesMember" xlink:title="pfg_CommonStockUnderlyingStockOptionsToExtentExercisedForSharePurchasesMember" />
    <link:definitionArc xlink:type="arc" xlink:from="ecd_AllTradingArrangementsMember" xlink:to="pfg_CommonStockUnderlyingStockOptionsToExtentExercisedForSharePurchasesMember" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:ecd_AllTradingArrangementsMember To pfg_CommonStockUnderlyingStockOptionsToExtentExercisedForSharePurchasesMember" order="1" priority="0" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetSharesReceivedUponVestingAfterTaxWithholdingFromRestrictedStockUnitMember" xlink:label="pfg_NetSharesReceivedUponVestingAfterTaxWithholdingFromRestrictedStockUnitMember" xlink:title="pfg_NetSharesReceivedUponVestingAfterTaxWithholdingFromRestrictedStockUnitMember" />
    <link:definitionArc xlink:type="arc" xlink:from="ecd_AllTradingArrangementsMember" xlink:to="pfg_NetSharesReceivedUponVestingAfterTaxWithholdingFromRestrictedStockUnitMember" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:ecd_AllTradingArrangementsMember To pfg_NetSharesReceivedUponVestingAfterTaxWithholdingFromRestrictedStockUnitMember" order="2" priority="0" />
    <link:loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PerformanceBasedStockUnitForTargetNumberMember" xlink:label="pfg_PerformanceBasedStockUnitForTargetNumberMember" xlink:title="pfg_PerformanceBasedStockUnitForTargetNumberMember" />
    <link:definitionArc xlink:type="arc" xlink:from="ecd_AllTradingArrangementsMember" xlink:to="pfg_PerformanceBasedStockUnitForTargetNumberMember" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:title="definition:ecd_AllTradingArrangementsMember To pfg_PerformanceBasedStockUnitForTargetNumberMember" order="3" priority="0" />
  </link:definitionLink>
  <definitionLink xlink:role="http://principal.com/role/StatementConsolidatedStatementsOfFinancialPositionParenthetical" xlink:type="extended" xlink:title="995200105 - Statement - Consolidated Statements of Financial Position (Parenthetical)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis" xlink:label="srt_ConsolidatedEntitiesAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_StatementTable" xlink:to="srt_ConsolidatedEntitiesAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain_639069372506812071" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain_639069372506812071" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:label="us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidatedEntitiesDomain" xlink:to="us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradingSecuritiesDebt" xlink:label="us-gaap_TradingSecuritiesDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TradingSecuritiesDebt" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent" xlink:label="us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" xlink:label="us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MortgageLoansOnRealEstateCommercialAndConsumerNetFairValueOption" xlink:label="pfg_MortgageLoansOnRealEstateCommercialAndConsumerNetFairValueOption" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_StatementLineItems" xlink:to="pfg_MortgageLoansOnRealEstateCommercialAndConsumerNetFairValueOption" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RealEstateInvestments" xlink:label="us-gaap_RealEstateInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_RealEstateInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherInvestments" xlink:label="us-gaap_OtherInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OtherInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherInvestmentsFairValueOption" xlink:label="pfg_OtherInvestmentsFairValueOption" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_StatementLineItems" xlink:to="pfg_OtherInvestmentsFairValueOption" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedInvestmentIncomeReceivable" xlink:label="us-gaap_AccruedInvestmentIncomeReceivable" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AccruedInvestmentIncomeReceivable" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountAssets" xlink:label="us-gaap_SeparateAccountAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_SeparateAccountAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermBorrowings" xlink:label="us-gaap_ShortTermBorrowings" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShortTermBorrowings" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountsLiability" xlink:label="us-gaap_SeparateAccountsLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_SeparateAccountsLiability" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLiabilities" xlink:label="us-gaap_OtherLiabilities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OtherLiabilities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" xlink:label="us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="15" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="16" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="us-gaap_CommonStockSharesAuthorized" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="17" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesAuthorized" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesIssued" xlink:label="us-gaap_CommonStockSharesIssued" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="18" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesIssued" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="us-gaap_CommonStockSharesOutstanding" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="19" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesOutstanding" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonShares" xlink:label="us-gaap_TreasuryStockCommonShares" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="20" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TreasuryStockCommonShares" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/StatementConsolidatedStatementsOfStockholdersEquity" xlink:type="extended" xlink:title="995200400 - Statement - Consolidated Statements of Stockholders' Equity" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementEquityComponentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_639069372506991798" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_639069372506991798" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="us-gaap_AdditionalPaidInCapitalMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AdditionalPaidInCapitalMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember" xlink:label="us-gaap_RetainedEarningsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_RetainedEarningsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonMember" xlink:label="us-gaap_TreasuryStockCommonMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_TreasuryStockCommonMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoncontrollingInterestMember" xlink:label="us-gaap_NoncontrollingInterestMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_NoncontrollingInterestMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="us-gaap_StockIssuedDuringPeriodValueNewIssues" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StockBasedCompensation" xlink:label="pfg_StockBasedCompensation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="pfg_StockBasedCompensation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:label="us-gaap_TreasuryStockValueAcquiredCostMethod" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="us-gaap_TreasuryStockValueAcquiredCostMethod" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsCommonStock" xlink:label="us-gaap_DividendsCommonStock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="us-gaap_DividendsCommonStock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:label="us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MinorityInterestIncreaseFromContributionsFromNoncontrollingInterest" xlink:label="pfg_MinorityInterestIncreaseFromContributionsFromNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="pfg_MinorityInterestIncreaseFromContributionsFromNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MinorityInterestDecreaseFromRedemptions" xlink:label="us-gaap_MinorityInterestDecreaseFromRedemptions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="us-gaap_MinorityInterestDecreaseFromRedemptions" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AdjustmentsToRedemptionAmountOfRedeemableNoncontrollingInterest" xlink:label="pfg_AdjustmentsToRedemptionAmountOfRedeemableNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="pfg_AdjustmentsToRedemptionAmountOfRedeemableNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoncontrollingInterestDecreaseFromDeconsolidation" xlink:label="us-gaap_NoncontrollingInterestDecreaseFromDeconsolidation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="us-gaap_NoncontrollingInterestDecreaseFromDeconsolidation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest" xlink:label="us-gaap_NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="us-gaap_NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherComprehensiveIncomeLossNetOfTaxExcludingRedeemableNoncontrollingInterest" xlink:label="pfg_OtherComprehensiveIncomeLossNetOfTaxExcludingRedeemableNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="pfg_OtherComprehensiveIncomeLossNetOfTaxExcludingRedeemableNoncontrollingInterest" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesTables" xlink:type="extended" xlink:title="99930703 - Disclosure - Deferred Acquisition Costs and Other Actuarial Balances (Tables)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372507129839" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372507129839" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostsTableTextBlock" xlink:label="us-gaap_DeferredPolicyAcquisitionCostsTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCostsTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ScheduleOfDisaggregatedUnearnedRevenueLiabilityAndReconciliationTableTextBlock" xlink:label="pfg_ScheduleOfDisaggregatedUnearnedRevenueLiabilityAndReconciliationTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_StatementLineItems" xlink:to="pfg_ScheduleOfDisaggregatedUnearnedRevenueLiabilityAndReconciliationTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_UnearnedRevenueLiabilityActivityTableTextBlock" xlink:label="pfg_UnearnedRevenueLiabilityActivityTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_StatementLineItems" xlink:to="pfg_UnearnedRevenueLiabilityActivityTableTextBlock" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSeparateAccountBalancesTables" xlink:type="extended" xlink:title="99930803 - Disclosure - Separate Account Balances (Tables)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372507129839" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372507129839" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372507290422" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372507290422" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_StatementTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372507290422" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372507290422" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentTextBlock" xlink:label="us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityTableTextBlock" xlink:label="us-gaap_SeparateAccountLiabilityTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_SeparateAccountLiabilityTableTextBlock" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureContractholderFundsTables" xlink:type="extended" xlink:title="99930903 - Disclosure - Contractholder Funds (Tables)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceTable" xlink:label="us-gaap_PolicyholderAccountBalanceTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372507290422" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372507290422" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_PolicyholderAccountBalanceTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372507290422" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372507290422" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_PolicyholderAccountBalanceTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372507290422" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372507290422" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceLineItems" xlink:label="us-gaap_PolicyholderAccountBalanceLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceLineItems" xlink:to="us-gaap_PolicyholderAccountBalanceTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ScheduleOfDisaggregatedPolicyholderAccountBalanceAmountsAndReconcileTotalsToContractholderFundsTableTextBlock" xlink:label="pfg_ScheduleOfDisaggregatedPolicyholderAccountBalanceAmountsAndReconcileTotalsToContractholderFundsTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PolicyholderAccountBalanceLineItems" xlink:to="pfg_ScheduleOfDisaggregatedPolicyholderAccountBalanceAmountsAndReconcileTotalsToContractholderFundsTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceTableTextBlock" xlink:label="us-gaap_PolicyholderAccountBalanceTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_PolicyholderAccountBalanceLineItems" xlink:to="us-gaap_PolicyholderAccountBalanceTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTableTextBlock" xlink:label="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_PolicyholderAccountBalanceLineItems" xlink:to="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTableTextBlock" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsTables" xlink:type="extended" xlink:title="99931003 - Disclosure - Future Policy Benefits and Claims (Tables)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372507290422" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372507290422" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372507446431" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372507446431" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372507446431" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372507446431" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LongTermDisabilityGroupLifeWaiverMember" xlink:label="pfg_LongTermDisabilityGroupLifeWaiverMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_LongTermDisabilityGroupLifeWaiverMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" xlink:label="pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GroupLifeMember" xlink:label="pfg_GroupLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_GroupLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitsAndUnpaidClaimsDisclosureTextBlock" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitsAndUnpaidClaimsDisclosureTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitsAndUnpaidClaimsDisclosureTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTableTextBlock" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitActivityTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense" xlink:label="us-gaap_ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsClaimsDevelopmentTableTextBlock" xlink:label="us-gaap_ShortdurationInsuranceContractsClaimsDevelopmentTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsClaimsDevelopmentTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTableTextBlock" xlink:label="us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsScheduleOfHistoricalClaimsDurationTableTextBlock" xlink:label="us-gaap_ShortdurationInsuranceContractsScheduleOfHistoricalClaimsDurationTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsScheduleOfHistoricalClaimsDurationTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ShortDurationInsuranceContractsDiscountedLiabilitiesTableTextBlock" xlink:label="pfg_ShortDurationInsuranceContractsDiscountedLiabilitiesTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="pfg_ShortDurationInsuranceContractsDiscountedLiabilitiesTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LiabilityForFuturePolicyBenefitGrossPremiumOrAssessmentAndInterestAccretionTableTextBlock" xlink:label="pfg_LiabilityForFuturePolicyBenefitGrossPremiumOrAssessmentAndInterestAccretionTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="pfg_LiabilityForFuturePolicyBenefitGrossPremiumOrAssessmentAndInterestAccretionTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceTableTextBlock" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LiabilityForFuturePolicyBenefitExpectedUndiscountedFutureBenefitPaymentsExpectedUndiscountedFutureGrossPremiumsAndExpectedDiscountedFutureGrossPremiumsTableTextBlock" xlink:label="pfg_LiabilityForFuturePolicyBenefitExpectedUndiscountedFutureBenefitPaymentsExpectedUndiscountedFutureGrossPremiumsAndExpectedDiscountedFutureGrossPremiumsTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="pfg_LiabilityForFuturePolicyBenefitExpectedUndiscountedFutureBenefitPaymentsExpectedUndiscountedFutureGrossPremiumsAndExpectedDiscountedFutureGrossPremiumsTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LiabilityForFuturePolicyBenefitWeightedAverageRatesOfInterestAccretionAndCurrentDiscountTableTextBlock" xlink:label="pfg_LiabilityForFuturePolicyBenefitWeightedAverageRatesOfInterestAccretionAndCurrentDiscountTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="pfg_LiabilityForFuturePolicyBenefitWeightedAverageRatesOfInterestAccretionAndCurrentDiscountTableTextBlock" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureMarketRiskBenefitsTables" xlink:type="extended" xlink:title="99931103 - Disclosure - Market Risk Benefits (Tables)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitTable" xlink:label="us-gaap_MarketRiskBenefitTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_MarketRiskBenefitTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372507446431" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372507446431" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_MarketRiskBenefitTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372507446431" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372507446431" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableAnnuityMember" xlink:label="us-gaap_VariableAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_VariableAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitLineItems" xlink:label="us-gaap_MarketRiskBenefitLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="us-gaap_MarketRiskBenefitTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MarketRiskBenefitAfterIncreaseDecreaseFromInstrumentSpecificCreditRiskTableTextBlock" xlink:label="pfg_MarketRiskBenefitAfterIncreaseDecreaseFromInstrumentSpecificCreditRiskTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="pfg_MarketRiskBenefitAfterIncreaseDecreaseFromInstrumentSpecificCreditRiskTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitActivityTableTextBlock" xlink:label="us-gaap_MarketRiskBenefitActivityTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="us-gaap_MarketRiskBenefitActivityTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SignificantChangesToInputsAndAssumptionsThatImpactedChangeInMarketRiskBenefitsFairValueMeasurementTableTextBlock" xlink:label="pfg_SignificantChangesToInputsAndAssumptionsThatImpactedChangeInMarketRiskBenefitsFairValueMeasurementTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="pfg_SignificantChangesToInputsAndAssumptionsThatImpactedChangeInMarketRiskBenefitsFairValueMeasurementTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsTables" xlink:type="extended" xlink:title="99931503 - Disclosure - Employee and Agent Benefits (Tables)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable" xlink:label="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable" xlink:to="us-gaap_RetirementPlanTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_639069372507603471" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_639069372507603471" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="us-gaap_PensionPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_PensionPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:label="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfNetFundedStatusTableTextBlock" xlink:label="us-gaap_ScheduleOfNetFundedStatusTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="us-gaap_ScheduleOfNetFundedStatusTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAccumulatedBenefitObligationsInExcessOfFairValueOfPlanAssetsTableTextBlock" xlink:label="us-gaap_ScheduleOfAccumulatedBenefitObligationsInExcessOfFairValueOfPlanAssetsTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="us-gaap_ScheduleOfAccumulatedBenefitObligationsInExcessOfFairValueOfPlanAssetsTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfNetBenefitCostsTableTextBlock" xlink:label="us-gaap_ScheduleOfNetBenefitCostsTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="us-gaap_ScheduleOfNetBenefitCostsTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAmountsRecognizedInOtherComprehensiveIncomeLossTableTextBlock" xlink:label="us-gaap_ScheduleOfAmountsRecognizedInOtherComprehensiveIncomeLossTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="us-gaap_ScheduleOfAmountsRecognizedInOtherComprehensiveIncomeLossTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ScheduleOfBenefitObligationAssumptionsUsedTableTextBlock" xlink:label="pfg_ScheduleOfBenefitObligationAssumptionsUsedTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="pfg_ScheduleOfBenefitObligationAssumptionsUsedTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ScheduleOfNetPeriodicBenefitCostAssumptionsUsedTableTextBlock" xlink:label="pfg_ScheduleOfNetPeriodicBenefitCostAssumptionsUsedTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="pfg_ScheduleOfNetPeriodicBenefitCostAssumptionsUsedTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfHealthCareCostTrendRatesTableTextBlock" xlink:label="us-gaap_ScheduleOfHealthCareCostTrendRatesTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="us-gaap_ScheduleOfHealthCareCostTrendRatesTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAllocationOfPlanAssetsTableTextBlock" xlink:label="us-gaap_ScheduleOfAllocationOfPlanAssetsTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="us-gaap_ScheduleOfAllocationOfPlanAssetsTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ScheduleOfTargetAllocationOfPlanAssetsTableTextBlock" xlink:label="pfg_ScheduleOfTargetAllocationOfPlanAssetsTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="pfg_ScheduleOfTargetAllocationOfPlanAssetsTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfExpectedBenefitPaymentsTableTextBlock" xlink:label="us-gaap_ScheduleOfExpectedBenefitPaymentsTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="us-gaap_ScheduleOfExpectedBenefitPaymentsTableTextBlock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ScheduleOfDefinedBenefitPensionPlansSupplementalInformationTableTextBlock" xlink:label="pfg_ScheduleOfDefinedBenefitPensionPlansSupplementalInformationTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="pfg_ScheduleOfDefinedBenefitPensionPlansSupplementalInformationTableTextBlock" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureRevenuesFromContractsWithCustomersTables" xlink:type="extended" xlink:title="99932103 - Disclosure - Revenues from Contracts with Customers (Tables)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="us-gaap_DisaggregationOfRevenueTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372507603471" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372507603471" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372507603471" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372507603471" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInvestmentManagementMember" xlink:label="pfg_SubsegmentInvestmentManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInvestmentManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentSpecialtyBenefitsMember" xlink:label="pfg_SubsegmentSpecialtyBenefitsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentSpecialtyBenefitsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="us-gaap_DisaggregationOfRevenueLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_DisaggregationOfRevenueTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:label="us-gaap_DisaggregationOfRevenueTableTextBlock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_DisaggregationOfRevenueTableTextBlock" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureNatureOfOperationsAndSignificantAccountingPoliciesContractholderAndPolicyholderLiabilitiesDetails" xlink:type="extended" xlink:title="99940102 - Disclosure - Nature of Operations and Significant Accounting Policies - Contractholder and Policyholder Liabilities (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372507718835" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372507718835" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentIndividualLifeInsuranceMember" xlink:label="pfg_SubsegmentIndividualLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentIndividualLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ParticipatingPoliciesAbstract" xlink:label="us-gaap_ParticipatingPoliciesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:to="us-gaap_ParticipatingPoliciesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ParticipatingPoliciesAsPercentageOfGrossInsuranceInForce" xlink:label="us-gaap_ParticipatingPoliciesAsPercentageOfGrossInsuranceInForce" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ParticipatingPoliciesAbstract" xlink:to="us-gaap_ParticipatingPoliciesAsPercentageOfGrossInsuranceInForce" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ParticipatingPoliciesAsPercentageOfNumberOfLifeInsurancePoliciesInForce" xlink:label="pfg_ParticipatingPoliciesAsPercentageOfNumberOfLifeInsurancePoliciesInForce" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ParticipatingPoliciesAbstract" xlink:to="pfg_ParticipatingPoliciesAsPercentageOfNumberOfLifeInsurancePoliciesInForce" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ParticipatingPolicyPercentageOfPremiumIncome" xlink:label="us-gaap_ParticipatingPolicyPercentageOfPremiumIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ParticipatingPoliciesAbstract" xlink:to="us-gaap_ParticipatingPolicyPercentageOfPremiumIncome" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureGoodwillAndOtherIntangibleAssetsChangesInGoodwillDetails" xlink:type="extended" xlink:title="99940201 - Disclosure - Goodwill and Other Intangible Assets - Changes in Goodwill (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="us-gaap_ScheduleOfGoodwillTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfGoodwillTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372507718835" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372507718835" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillLineItems" xlink:label="us-gaap_GoodwillLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_GoodwillLineItems" xlink:to="us-gaap_ScheduleOfGoodwillTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillRollForward" xlink:label="us-gaap_GoodwillRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_GoodwillLineItems" xlink:to="us-gaap_GoodwillRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_GoodwillRollForward" xlink:to="us-gaap_Goodwill" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillAcquiredDuringPeriod" xlink:label="us-gaap_GoodwillAcquiredDuringPeriod" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_GoodwillRollForward" xlink:to="us-gaap_GoodwillAcquiredDuringPeriod" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:label="us-gaap_GoodwillForeignCurrencyTranslationGainLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_GoodwillRollForward" xlink:to="us-gaap_GoodwillForeignCurrencyTranslationGainLoss" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureGoodwillAndOtherIntangibleAssetsFiniteLivedIntangibleAssetsDetails" xlink:type="extended" xlink:title="99940202 - Disclosure - Goodwill and Other Intangible Assets - Finite-Lived Intangible Assets (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639069372507718835" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639069372507718835" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherIntangibleAssetsMember" xlink:label="us-gaap_OtherIntangibleAssetsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_OtherIntangibleAssetsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="us-gaap_FiniteLivedIntangibleAssetsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FiniteLivedIntangibleAssetsWeightedAverageRemainingExpectedLife" xlink:label="pfg_FiniteLivedIntangibleAssetsWeightedAverageRemainingExpectedLife" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="pfg_FiniteLivedIntangibleAssetsWeightedAverageRemainingExpectedLife" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_FiniteLivedIntangibleAssetsGross" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FiniteLivedIntangibleAssetsFullyAmortizedBalance" xlink:label="pfg_FiniteLivedIntangibleAssetsFullyAmortizedBalance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="pfg_FiniteLivedIntangibleAssetsFullyAmortizedBalance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="us-gaap_AmortizationOfIntangibleAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_AmortizationOfIntangibleAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" xlink:label="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureGoodwillAndOtherIntangibleAssetsAdditionalInformationDetails" xlink:type="extended" xlink:title="99940203 - Disclosure - Goodwill and Other Intangible Assets - Additional Information (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639069372507921994" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639069372507921994" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DistributionRightsMember" xlink:label="us-gaap_DistributionRightsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_DistributionRightsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="us-gaap_CustomerRelationshipsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_CustomerRelationshipsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="us-gaap_IncomeStatementLocationAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="us-gaap_IncomeStatementLocationAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain_639069372507921994" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain_639069372507921994" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnInvestmentsMember1" xlink:label="us-gaap_GainLossOnInvestmentsMember1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_GainLossOnInvestmentsMember1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="us-gaap_FiniteLivedIntangibleAssetsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfIntangibleAssetsFinitelived" xlink:label="us-gaap_ImpairmentOfIntangibleAssetsFinitelived" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_ImpairmentOfIntangibleAssetsFinitelived" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfIntangibleAssetFiniteLivedStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" xlink:label="us-gaap_ImpairmentOfIntangibleAssetFiniteLivedStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ImpairmentOfIntangibleAssetsFinitelived" xlink:to="us-gaap_ImpairmentOfIntangibleAssetFiniteLivedStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnDispositionOfIntangibleAssets" xlink:label="us-gaap_GainLossOnDispositionOfIntangibleAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_GainLossOnDispositionOfIntangibleAssets" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureGoodwillAndOtherIntangibleAssetsIndefiniteLivedIntangibleAssetsDetails" xlink:type="extended" xlink:title="99940204 - Disclosure - Goodwill and Other Intangible Assets - Indefinite-Lived Intangible Assets (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable" xlink:label="us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="us-gaap_BusinessAcquisitionAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable" xlink:to="us-gaap_BusinessAcquisitionAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain_639069372508078141" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain_639069372508078141" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_WMAdvisorsMember" xlink:label="pfg_WMAdvisorsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="pfg_WMAdvisorsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems" xlink:to="us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems" xlink:to="us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureVariableInterestEntitiesConsolidatedViesDetails" xlink:type="extended" xlink:title="99940301 - Disclosure - Variable Interest Entities - Consolidated VIEs (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ConsolidatedVariableInterestEntityAssetsLiabilitiesTable" xlink:label="pfg_ConsolidatedVariableInterestEntityAssetsLiabilitiesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis" xlink:label="srt_ConsolidatedEntitiesAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_ConsolidatedVariableInterestEntityAssetsLiabilitiesTable" xlink:to="srt_ConsolidatedEntitiesAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain_639069372508078141" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain_639069372508078141" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:label="us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidatedEntitiesDomain" xlink:to="us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_VariableInterestEntityPrimaryBeneficiaryMandatoryRetirementSavingsMember" xlink:label="pfg_VariableInterestEntityPrimaryBeneficiaryMandatoryRetirementSavingsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:to="pfg_VariableInterestEntityPrimaryBeneficiaryMandatoryRetirementSavingsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_VariableInterestEntityPrimaryBeneficiaryRealEstateMember" xlink:label="pfg_VariableInterestEntityPrimaryBeneficiaryRealEstateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:to="pfg_VariableInterestEntityPrimaryBeneficiaryRealEstateMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_VariableInterestEntityPrimaryBeneficiarySponsoredInvestmentFundsMember" xlink:label="pfg_VariableInterestEntityPrimaryBeneficiarySponsoredInvestmentFundsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:to="pfg_VariableInterestEntityPrimaryBeneficiarySponsoredInvestmentFundsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_VariableInterestEntityPrimaryBeneficiaryResidentialMortgageLoansMember" xlink:label="pfg_VariableInterestEntityPrimaryBeneficiaryResidentialMortgageLoansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:to="pfg_VariableInterestEntityPrimaryBeneficiaryResidentialMortgageLoansMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_VariableInterestEntityPrimaryBeneficiaryAssetBackedLimitedPartnershipMember" xlink:label="pfg_VariableInterestEntityPrimaryBeneficiaryAssetBackedLimitedPartnershipMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:to="pfg_VariableInterestEntityPrimaryBeneficiaryAssetBackedLimitedPartnershipMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableInterestEntityLineItems" xlink:label="us-gaap_VariableInterestEntityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_VariableInterestEntityLineItems" xlink:to="pfg_ConsolidatedVariableInterestEntityAssetsLiabilitiesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_VariableInterestEntityLineItems" xlink:to="us-gaap_Assets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities" xlink:label="us-gaap_Liabilities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_VariableInterestEntityLineItems" xlink:to="us-gaap_Liabilities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" xlink:label="us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_VariableInterestEntityLineItems" xlink:to="us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureVariableInterestEntitiesUnconsolidatedViesDetails" xlink:type="extended" xlink:title="99940302 - Disclosure - Variable Interest Entities - Unconsolidated VIEs (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_UnconsolidatedVariableInterestEntityAssetsTable" xlink:label="pfg_UnconsolidatedVariableInterestEntityAssetsTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeAxis" xlink:label="us-gaap_InvestmentTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_UnconsolidatedVariableInterestEntityAssetsTable" xlink:to="us-gaap_InvestmentTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember_639069372508078141" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember_639069372508078141" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesMember" xlink:label="us-gaap_DebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_DebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="us-gaap_CorporateDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CorporateDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember" xlink:label="us-gaap_ResidentialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_ResidentialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember" xlink:label="us-gaap_CommercialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CommercialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralizedDebtObligationsMember" xlink:label="us-gaap_CollateralizedDebtObligationsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CollateralizedDebtObligationsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherDebtSecuritiesMember" xlink:label="us-gaap_OtherDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_OtherDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesMember" xlink:label="us-gaap_EquitySecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_EquitySecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherLimitedPartnershipAndFundInterestsMember" xlink:label="pfg_OtherLimitedPartnershipAndFundInterestsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="pfg_OtherLimitedPartnershipAndFundInterestsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_UnconsolidatedVariableInterestEntityAssetsTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372508234377" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372508234377" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AvailableForSaleSecurityMember" xlink:label="pfg_AvailableForSaleSecurityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_AvailableForSaleSecurityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TradingSecuritiesMember" xlink:label="pfg_TradingSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_TradingSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis" xlink:label="srt_ConsolidatedEntitiesAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="pfg_UnconsolidatedVariableInterestEntityAssetsTable" xlink:to="srt_ConsolidatedEntitiesAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain_639069372508234377" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain_639069372508234377" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember" xlink:label="us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidatedEntitiesDomain" xlink:to="us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_UnconsolidatedVariableInterestEntityLineItems" xlink:label="pfg_UnconsolidatedVariableInterestEntityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_UnconsolidatedVariableInterestEntityLineItems" xlink:to="pfg_UnconsolidatedVariableInterestEntityAssetsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_UnconsolidatedVariableInterestEntityLineItems" xlink:to="us-gaap_Assets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount" xlink:label="us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_UnconsolidatedVariableInterestEntityLineItems" xlink:to="us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AssetCarryingValueUsedIfDistributionsReceivedInExcessOfInvestment" xlink:label="pfg_AssetCarryingValueUsedIfDistributionsReceivedInExcessOfInvestment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_UnconsolidatedVariableInterestEntityLineItems" xlink:to="pfg_AssetCarryingValueUsedIfDistributionsReceivedInExcessOfInvestment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_VariableInterestEntityFullySecuredDebtOfInternationalRealEstateFundsIncludedInMaximumLossExposureAmount" xlink:label="pfg_VariableInterestEntityFullySecuredDebtOfInternationalRealEstateFundsIncludedInMaximumLossExposureAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_UnconsolidatedVariableInterestEntityLineItems" xlink:to="pfg_VariableInterestEntityFullySecuredDebtOfInternationalRealEstateFundsIncludedInMaximumLossExposureAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MoneyMarketFundsAbstract" xlink:label="pfg_MoneyMarketFundsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_UnconsolidatedVariableInterestEntityLineItems" xlink:to="pfg_MoneyMarketFundsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TotalAssetsUnconsolidatedMoneyMarketMutualFund" xlink:label="pfg_TotalAssetsUnconsolidatedMoneyMarketMutualFund" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_MoneyMarketFundsAbstract" xlink:to="pfg_TotalAssetsUnconsolidatedMoneyMarketMutualFund" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsFixedMaturitiesDetails" xlink:type="extended" xlink:title="99940401 - Disclosure - Investments - Fixed Maturities (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketableSecuritiesTable" xlink:label="us-gaap_MarketableSecuritiesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_MarketableSecuritiesTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372508234377" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372508234377" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasuryAndGovernmentMember" xlink:label="us-gaap_USTreasuryAndGovernmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_USTreasuryAndGovernmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignGovernmentDebtSecuritiesMember" xlink:label="us-gaap_ForeignGovernmentDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_ForeignGovernmentDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember" xlink:label="us-gaap_USStatesAndPoliticalSubdivisionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_USStatesAndPoliticalSubdivisionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="us-gaap_CorporateDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CorporateDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember" xlink:label="us-gaap_ResidentialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_ResidentialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember" xlink:label="us-gaap_CommercialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CommercialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralizedDebtObligationsMember" xlink:label="us-gaap_CollateralizedDebtObligationsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CollateralizedDebtObligationsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherDebtSecuritiesMember" xlink:label="us-gaap_OtherDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_OtherDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketableSecuritiesLineItems" xlink:label="us-gaap_MarketableSecuritiesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="us-gaap_MarketableSecuritiesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax" xlink:label="us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax" xlink:label="us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossBeforePortfolioLayerMethodBasisAdjustment" xlink:label="pfg_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossBeforePortfolioLayerMethodBasisAdjustment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="pfg_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossBeforePortfolioLayerMethodBasisAdjustment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainBeforePortfolioLayerMethodBasisAdjustment" xlink:label="pfg_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainBeforePortfolioLayerMethodBasisAdjustment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="pfg_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainBeforePortfolioLayerMethodBasisAdjustment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedLossBeforePortfolioLayerMethodBasisAdjustment" xlink:label="pfg_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedLossBeforePortfolioLayerMethodBasisAdjustment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="pfg_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedLossBeforePortfolioLayerMethodBasisAdjustment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleAllowanceForCreditLossExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustment" xlink:label="pfg_DebtSecuritiesAvailableForSaleAllowanceForCreditLossExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="pfg_DebtSecuritiesAvailableForSaleAllowanceForCreditLossExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustment" xlink:label="pfg_DebtSecuritiesAvailableForSaleExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="pfg_DebtSecuritiesAvailableForSaleExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossPortfolioLayerMethodBasisAdjustment" xlink:label="pfg_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossPortfolioLayerMethodBasisAdjustment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="pfg_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossPortfolioLayerMethodBasisAdjustment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainPortfolioLayerMethodBasisAdjustment" xlink:label="pfg_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainPortfolioLayerMethodBasisAdjustment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="pfg_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainPortfolioLayerMethodBasisAdjustment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestReceivable" xlink:label="us-gaap_InterestReceivable" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="us-gaap_InterestReceivable" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsNetInvestmentIncomeDetails" xlink:type="extended" xlink:title="99940403 - Disclosure - Investments - Net Investment Income (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryTable" xlink:label="us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeAxis" xlink:label="us-gaap_InvestmentTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryTable" xlink:to="us-gaap_InvestmentTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember_639069372508398309" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember_639069372508398309" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesMember" xlink:label="us-gaap_DebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_DebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesMember" xlink:label="us-gaap_EquitySecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_EquitySecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MortgageLoansMember" xlink:label="pfg_MortgageLoansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="pfg_MortgageLoansMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentsInRealEstateMember" xlink:label="pfg_InvestmentsInRealEstateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="pfg_InvestmentsInRealEstateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyLoansMember" xlink:label="us-gaap_PolicyLoansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_PolicyLoansMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsMember" xlink:label="us-gaap_CashAndCashEquivalentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_CashAndCashEquivalentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeMember" xlink:label="us-gaap_DerivativeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_DerivativeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherInvestmentTypesMember" xlink:label="pfg_OtherInvestmentTypesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="pfg_OtherInvestmentTypesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372508398309" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372508398309" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AvailableForSaleSecurityMember" xlink:label="pfg_AvailableForSaleSecurityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_AvailableForSaleSecurityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TradingSecuritiesMember" xlink:label="pfg_TradingSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_TradingSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryLineItems" xlink:label="us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryLineItems" xlink:to="us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GrossInvestmentIncomeLoss" xlink:label="pfg_GrossInvestmentIncomeLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryLineItems" xlink:to="pfg_GrossInvestmentIncomeLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeInvestmentExpense" xlink:label="us-gaap_InvestmentIncomeInvestmentExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryLineItems" xlink:to="us-gaap_InvestmentIncomeInvestmentExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentIncome" xlink:label="us-gaap_NetInvestmentIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ScheduleOfInvestmentIncomeReportedAmountsByCategoryLineItems" xlink:to="us-gaap_NetInvestmentIncome" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsAllowanceForCreditLossDetails" xlink:type="extended" xlink:title="99940405 - Disclosure - Investments - Allowance for Credit Loss (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossTable" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372508398309" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372508398309" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasuryAndGovernmentMember" xlink:label="us-gaap_USTreasuryAndGovernmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_USTreasuryAndGovernmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="us-gaap_CorporateDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CorporateDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember" xlink:label="us-gaap_CommercialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CommercialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralizedDebtObligationsMember" xlink:label="us-gaap_CollateralizedDebtObligationsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CollateralizedDebtObligationsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherDebtSecuritiesMember" xlink:label="us-gaap_OtherDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_OtherDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableforsaleAllowanceForCreditLossLineItems" xlink:label="us-gaap_DebtSecuritiesAvailableforsaleAllowanceForCreditLossLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DebtSecuritiesAvailableforsaleAllowanceForCreditLossLineItems" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtSecuritiesAvailableforsaleAllowanceForCreditLossLineItems" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotPreviouslyRecorded" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotPreviouslyRecorded" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotPreviouslyRecorded" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossSecuritiesSold" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossSecuritiesSold" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossSecuritiesSold" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossWriteoff" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossWriteoff" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossWriteoff" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslationAdjustment" xlink:label="pfg_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslationAdjustment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossRollForward" xlink:to="pfg_DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslationAdjustment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAccruedInterestWriteoff" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleAccruedInterestWriteoff" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtSecuritiesAvailableforsaleAllowanceForCreditLossLineItems" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleAccruedInterestWriteoff" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsGrossUnrealizedLossesForFixedMaturitiesDetails" xlink:type="extended" xlink:title="99940406 - Disclosure - Investments - Gross Unrealized Losses for Fixed Maturities (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketableSecuritiesTable" xlink:label="us-gaap_MarketableSecuritiesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_MarketableSecuritiesTable" xlink:to="dei_LegalEntityAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_639069372508548817" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_639069372508548817" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PrincipalLifeInsuranceCompanyConsolidatedMember" xlink:label="pfg_PrincipalLifeInsuranceCompanyConsolidatedMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="dei_EntityDomain" xlink:to="pfg_PrincipalLifeInsuranceCompanyConsolidatedMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_MarketableSecuritiesTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372508548817" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372508548817" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasuryAndGovernmentMember" xlink:label="us-gaap_USTreasuryAndGovernmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_USTreasuryAndGovernmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignGovernmentDebtSecuritiesMember" xlink:label="us-gaap_ForeignGovernmentDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_ForeignGovernmentDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember" xlink:label="us-gaap_USStatesAndPoliticalSubdivisionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_USStatesAndPoliticalSubdivisionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="us-gaap_CorporateDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CorporateDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember" xlink:label="us-gaap_ResidentialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_ResidentialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember" xlink:label="us-gaap_CommercialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CommercialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageBackedSecuritiesMember" xlink:label="us-gaap_MortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_MortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralizedDebtObligationsMember" xlink:label="us-gaap_CollateralizedDebtObligationsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CollateralizedDebtObligationsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherDebtSecuritiesMember" xlink:label="us-gaap_OtherDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_OtherDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketableSecuritiesLineItems" xlink:label="us-gaap_MarketableSecuritiesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="us-gaap_MarketableSecuritiesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract" xlink:label="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureAbstract" xlink:label="pfg_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_MarketableSecuritiesLineItems" xlink:to="pfg_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsPercentInvestmentGrade" xlink:label="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsPercentInvestmentGrade" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureAbstract" xlink:to="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsPercentInvestmentGrade" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsAveragePrice" xlink:label="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsAveragePrice" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureAbstract" xlink:to="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsAveragePrice" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureAbstract" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsAveragePriceLessThanTwelveMonths" xlink:label="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsAveragePriceLessThanTwelveMonths" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureAbstract" xlink:to="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsAveragePriceLessThanTwelveMonths" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsPercentInvestmentGradeLessThanTwelveMonths" xlink:label="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsPercentInvestmentGradeLessThanTwelveMonths" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureAbstract" xlink:to="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsPercentInvestmentGradeLessThanTwelveMonths" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossContinuousUnrealizedLossPositionAggregateLossesOnInvestmentGradeInvestmentsLessThanTwelveMonths" xlink:label="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossContinuousUnrealizedLossPositionAggregateLossesOnInvestmentGradeInvestmentsLessThanTwelveMonths" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureAbstract" xlink:to="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossContinuousUnrealizedLossPositionAggregateLossesOnInvestmentGradeInvestmentsLessThanTwelveMonths" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="pfg_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureAbstract" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsAveragePriceTwelveMonthsOrLonger" xlink:label="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsAveragePriceTwelveMonthsOrLonger" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="pfg_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureAbstract" xlink:to="pfg_DebtSecuritiesAvailableForSaleSecuritiesWithoutAllowanceForCreditLossUnrealizedLossPositionsAveragePriceTwelveMonthsOrLonger" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsMortgageLoanCreditMonitoringDetails" xlink:type="extended" xlink:title="99940408 - Disclosure - Investments - Mortgage Loan Credit Monitoring (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable" xlink:label="us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentDomain_639069372508722929" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentDomain_639069372508722929" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember" xlink:label="us-gaap_CommercialRealEstatePortfolioSegmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="us-gaap_CommercialRealEstatePortfolioSegmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResidentialMortgageMember" xlink:label="us-gaap_ResidentialMortgageMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="us-gaap_ResidentialMortgageMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConsumerPortfolioSegmentMember" xlink:label="us-gaap_ConsumerPortfolioSegmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="us-gaap_ConsumerPortfolioSegmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CreditRatingStandardPoorsAxis" xlink:label="srt_CreditRatingStandardPoorsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable" xlink:to="srt_CreditRatingStandardPoorsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ExternalCreditRatingStandardPoorsMember" xlink:label="srt_ExternalCreditRatingStandardPoorsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_CreditRatingStandardPoorsAxis" xlink:to="srt_ExternalCreditRatingStandardPoorsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ExternalCreditRatingStandardPoorsMember" xlink:label="srt_ExternalCreditRatingStandardPoorsMember_639069372508731723" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_CreditRatingStandardPoorsAxis" xlink:to="srt_ExternalCreditRatingStandardPoorsMember_639069372508731723" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StandardPoorsAMinusAndAboveRatingMember" xlink:label="pfg_StandardPoorsAMinusAndAboveRatingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ExternalCreditRatingStandardPoorsMember" xlink:to="pfg_StandardPoorsAMinusAndAboveRatingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StandardPoorsBBBPlusThruBBBMinusRatingMember" xlink:label="pfg_StandardPoorsBBBPlusThruBBBMinusRatingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ExternalCreditRatingStandardPoorsMember" xlink:to="pfg_StandardPoorsBBBPlusThruBBBMinusRatingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StandardPoorsBBPlusThruBBMinusRatingMember" xlink:label="pfg_StandardPoorsBBPlusThruBBMinusRatingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ExternalCreditRatingStandardPoorsMember" xlink:to="pfg_StandardPoorsBBPlusThruBBMinusRatingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StandardPoorsBPlusAndBelowRatingMember" xlink:label="pfg_StandardPoorsBPlusAndBelowRatingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ExternalCreditRatingStandardPoorsMember" xlink:to="pfg_StandardPoorsBPlusAndBelowRatingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentPerformanceStatusAxis" xlink:label="us-gaap_FinancialInstrumentPerformanceStatusAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable" xlink:to="us-gaap_FinancialInstrumentPerformanceStatusAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentPerformanceStatusDomain" xlink:label="us-gaap_FinancialInstrumentPerformanceStatusDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentPerformanceStatusAxis" xlink:to="us-gaap_FinancialInstrumentPerformanceStatusDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentPerformanceStatusDomain" xlink:label="us-gaap_FinancialInstrumentPerformanceStatusDomain_639069372508739145" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentPerformanceStatusAxis" xlink:to="us-gaap_FinancialInstrumentPerformanceStatusDomain_639069372508739145" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PerformingMember" xlink:label="pfg_PerformingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FinancialInstrumentPerformanceStatusDomain" xlink:to="pfg_PerformingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NonperformingMember" xlink:label="pfg_NonperformingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancialInstrumentPerformanceStatusDomain" xlink:to="pfg_NonperformingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableRecordedInvestmentLineItems" xlink:label="us-gaap_FinancingReceivableRecordedInvestmentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentLineItems" xlink:to="us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentLineItems" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestYearSixOriginatedFiveYearsBeforeCurrentFiscalYear" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestYearSixOriginatedFiveYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestYearSixOriginatedFiveYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanSixYearsBeforeCurrentFiscalYear" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanSixYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanSixYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustmentYearOneOriginatedCurrentFiscalYear" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustmentYearOneOriginatedCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustmentYearOneOriginatedCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestYearTwoBeforePortfolioLayerMethodBasisAdjustmentOriginatedFiscalYearBeforeCurrentFiscalYear" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestYearTwoBeforePortfolioLayerMethodBasisAdjustmentOriginatedFiscalYearBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestYearTwoBeforePortfolioLayerMethodBasisAdjustmentOriginatedFiscalYearBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestYearThreeBeforePortfolioLayerMethodBasisAdjustmentOriginatedTwoYearsBeforeCurrentFiscalYear" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestYearThreeBeforePortfolioLayerMethodBasisAdjustmentOriginatedTwoYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestYearThreeBeforePortfolioLayerMethodBasisAdjustmentOriginatedTwoYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestYearFourBeforePortfolioLayerMethodBasisAdjustmentOriginatedThreeYearsBeforeCurrentFiscalYear" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestYearFourBeforePortfolioLayerMethodBasisAdjustmentOriginatedThreeYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestYearFourBeforePortfolioLayerMethodBasisAdjustmentOriginatedThreeYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestYearFiveBeforePortfolioLayerMethodBasisAdjustmentOriginatedFourYearsBeforeCurrentFiscalYear" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestYearFiveBeforePortfolioLayerMethodBasisAdjustmentOriginatedFourYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestYearFiveBeforePortfolioLayerMethodBasisAdjustmentOriginatedFourYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestYearSixBeforePortfolioLayerMethodBasisAdjustmentOriginatedFiveYearsBeforeCurrentFiscalYear" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestYearSixBeforePortfolioLayerMethodBasisAdjustmentOriginatedFiveYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestYearSixBeforePortfolioLayerMethodBasisAdjustmentOriginatedFiveYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustmentOriginatedMoreThanSixYearsBeforeCurrentFiscalYear" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustmentOriginatedMoreThanSixYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="15" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustmentOriginatedMoreThanSixYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustmentOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustmentOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="16" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestBeforePortfolioLayerMethodBasisAdjustmentOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossBeforePortfolioLayerMethodBasisAdjustment" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossBeforePortfolioLayerMethodBasisAdjustment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="17" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossBeforePortfolioLayerMethodBasisAdjustment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossPortfolioLayerMethodBasisAdjustment" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossPortfolioLayerMethodBasisAdjustment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="18" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossPortfolioLayerMethodBasisAdjustment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="19" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" xlink:label="us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentLineItems" xlink:to="us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedInCurrentFiscalYear" xlink:label="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedInCurrentFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" xlink:to="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedInCurrentFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedInFiscalYearBeforeLatestFiscalYear" xlink:label="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedInFiscalYearBeforeLatestFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" xlink:to="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedInFiscalYearBeforeLatestFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedTwoYearsBeforeLatestFiscalYear" xlink:label="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedTwoYearsBeforeLatestFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" xlink:to="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedTwoYearsBeforeLatestFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedThreeYearsBeforeLatestFiscalYear" xlink:label="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedThreeYearsBeforeLatestFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" xlink:to="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedThreeYearsBeforeLatestFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedFourYearsBeforeLatestFiscalYear" xlink:label="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedFourYearsBeforeLatestFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" xlink:to="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedFourYearsBeforeLatestFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DirectFinancingLeaseNetInvestmentInLeaseOriginatedFiveYearsBeforeLatestFiscalYear" xlink:label="pfg_DirectFinancingLeaseNetInvestmentInLeaseOriginatedFiveYearsBeforeLatestFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" xlink:to="pfg_DirectFinancingLeaseNetInvestmentInLeaseOriginatedFiveYearsBeforeLatestFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DirectFinancingLeaseNetInvestmentInLeaseOriginatedSixOrMoreYearsBeforeLatestFiscalYear" xlink:label="pfg_DirectFinancingLeaseNetInvestmentInLeaseOriginatedSixOrMoreYearsBeforeLatestFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" xlink:to="pfg_DirectFinancingLeaseNetInvestmentInLeaseOriginatedSixOrMoreYearsBeforeLatestFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedFiveOrMoreYearsBeforeLatestFiscalYear" xlink:label="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedFiveOrMoreYearsBeforeLatestFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" xlink:to="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseOriginatedFiveOrMoreYearsBeforeLatestFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss" xlink:label="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_DirectFinancingLeaseNetInvestmentInLeasesAbstract" xlink:to="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsuranceRecoverablesGross" xlink:label="us-gaap_ReinsuranceRecoverablesGross" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentLineItems" xlink:to="us-gaap_ReinsuranceRecoverablesGross" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DirectFinancingLeaseInterestReceivable" xlink:label="pfg_DirectFinancingLeaseInterestReceivable" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentLineItems" xlink:to="pfg_DirectFinancingLeaseInterestReceivable" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MortgageLoansAndOtherLoansAbstract" xlink:label="pfg_MortgageLoansAndOtherLoansAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentLineItems" xlink:to="pfg_MortgageLoansAndOtherLoansAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestReceivable" xlink:label="us-gaap_InterestReceivable" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_MortgageLoansAndOtherLoansAbstract" xlink:to="us-gaap_InterestReceivable" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DaysDelinquentNonperforming" xlink:label="pfg_DaysDelinquentNonperforming" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_MortgageLoansAndOtherLoansAbstract" xlink:to="pfg_DaysDelinquentNonperforming" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsFinancingReceivableNonAccrualAndAgingDetails" xlink:type="extended" xlink:title="99940409 - Disclosure - Investments - Financing Receivable, Non-Accrual and Aging (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFinancingReceivablesPastDueTable" xlink:label="us-gaap_ScheduleOfFinancingReceivablesPastDueTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfFinancingReceivablesPastDueTable" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentDomain_639069372509171072" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentDomain_639069372509171072" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember" xlink:label="us-gaap_CommercialRealEstatePortfolioSegmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="us-gaap_CommercialRealEstatePortfolioSegmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResidentialMortgageMember" xlink:label="us-gaap_ResidentialMortgageMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="us-gaap_ResidentialMortgageMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConsumerPortfolioSegmentMember" xlink:label="us-gaap_ConsumerPortfolioSegmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="us-gaap_ConsumerPortfolioSegmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablesPeriodPastDueAxis" xlink:label="us-gaap_FinancingReceivablesPeriodPastDueAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfFinancingReceivablesPastDueTable" xlink:to="us-gaap_FinancingReceivablesPeriodPastDueAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain" xlink:label="us-gaap_FinancingReceivablesPeriodPastDueDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancingReceivablesPeriodPastDueAxis" xlink:to="us-gaap_FinancingReceivablesPeriodPastDueDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain" xlink:label="us-gaap_FinancingReceivablesPeriodPastDueDomain_639069372509171503" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancingReceivablesPeriodPastDueAxis" xlink:to="us-gaap_FinancingReceivablesPeriodPastDueDomain_639069372509171503" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialAssetPastDueMember" xlink:label="us-gaap_FinancialAssetPastDueMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FinancingReceivablesPeriodPastDueDomain" xlink:to="us-gaap_FinancialAssetPastDueMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivables30To59DaysPastDueMember" xlink:label="us-gaap_FinancingReceivables30To59DaysPastDueMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancingReceivablesPeriodPastDueDomain" xlink:to="us-gaap_FinancingReceivables30To59DaysPastDueMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivables60To89DaysPastDueMember" xlink:label="us-gaap_FinancingReceivables60To89DaysPastDueMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FinancingReceivablesPeriodPastDueDomain" xlink:to="us-gaap_FinancingReceivables60To89DaysPastDueMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember" xlink:label="us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FinancingReceivablesPeriodPastDueDomain" xlink:to="us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialAssetNotPastDueMember" xlink:label="us-gaap_FinancialAssetNotPastDueMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FinancingReceivablesPeriodPastDueDomain" xlink:to="us-gaap_FinancialAssetNotPastDueMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:label="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="us-gaap_ScheduleOfFinancingReceivablesPastDueTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableAndNetInvestmentInLeaseRecordedInvestmentNonaccrualStatus" xlink:label="pfg_FinancingReceivableAndNetInvestmentInLeaseRecordedInvestmentNonaccrualStatus" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="pfg_FinancingReceivableAndNetInvestmentInLeaseRecordedInvestmentNonaccrualStatus" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableAndNetInvestmentInLeaseNonaccrualNoAllowance" xlink:label="pfg_FinancingReceivableAndNetInvestmentInLeaseNonaccrualNoAllowance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="pfg_FinancingReceivableAndNetInvestmentInLeaseNonaccrualNoAllowance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableNonaccrualInterestIncome" xlink:label="us-gaap_FinancingReceivableNonaccrualInterestIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="us-gaap_FinancingReceivableNonaccrualInterestIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableExcludingAccruedInterestAndUnallocatedBasisAdjustmentsBeforeAllowanceForCreditLoss" xlink:label="pfg_FinancingReceivableExcludingAccruedInterestAndUnallocatedBasisAdjustmentsBeforeAllowanceForCreditLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="pfg_FinancingReceivableExcludingAccruedInterestAndUnallocatedBasisAdjustmentsBeforeAllowanceForCreditLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss" xlink:label="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss" xlink:label="pfg_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="pfg_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruingExcludingUnallocatedBasisAdjustments" xlink:label="pfg_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruingExcludingUnallocatedBasisAdjustments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="pfg_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruingExcludingUnallocatedBasisAdjustments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing" xlink:label="us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableAndNetInvestmentInLeaseRecordedInvestment90DaysPastDueAndStillAccruing" xlink:label="pfg_FinancingReceivableAndNetInvestmentInLeaseRecordedInvestment90DaysPastDueAndStillAccruing" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="pfg_FinancingReceivableAndNetInvestmentInLeaseRecordedInvestment90DaysPastDueAndStillAccruing" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsuranceRecoverablesGross" xlink:label="us-gaap_ReinsuranceRecoverablesGross" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems" xlink:to="us-gaap_ReinsuranceRecoverablesGross" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsMortgageLoanValuationAllowanceDetails" xlink:type="extended" xlink:title="99940410 - Disclosure - Investments - Mortgage Loan Valuation Allowance (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable" xlink:label="us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentDomain_639069372509199850" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentDomain_639069372509199850" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember" xlink:label="us-gaap_CommercialRealEstatePortfolioSegmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="us-gaap_CommercialRealEstatePortfolioSegmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResidentialMortgageMember" xlink:label="us-gaap_ResidentialMortgageMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="us-gaap_ResidentialMortgageMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ReinsuranceRecoverablesMember" xlink:label="pfg_ReinsuranceRecoverablesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="pfg_ReinsuranceRecoverablesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConsumerPortfolioSegmentMember" xlink:label="us-gaap_ConsumerPortfolioSegmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="us-gaap_ConsumerPortfolioSegmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems" xlink:label="us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems" xlink:to="us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest" xlink:label="us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward" xlink:to="us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslation" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" xlink:label="pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems" xlink:to="pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectFinancingLeaseNetInvestmentInLeaseAllowanceForCreditLossExcludingAccruedInterest" xlink:label="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseAllowanceForCreditLossExcludingAccruedInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" xlink:to="us-gaap_DirectFinancingLeaseNetInvestmentInLeaseAllowanceForCreditLossExcludingAccruedInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestCreditLossExpenseReversal" xlink:label="pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestCreditLossExpenseReversal" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" xlink:to="pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestCreditLossExpenseReversal" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslation" xlink:label="pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" xlink:to="pfg_DirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" xlink:label="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems" xlink:to="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestCreditLossExpenseReversal" xlink:label="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestCreditLossExpenseReversal" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" xlink:to="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestCreditLossExpenseReversal" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossWriteOff" xlink:label="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossWriteOff" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" xlink:to="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossWriteOff" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRecovery" xlink:label="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRecovery" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" xlink:to="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRecovery" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslation" xlink:label="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRollforward" xlink:to="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossForeignCurrencyTranslation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DaysDelinquentValuationAllowance" xlink:label="pfg_DaysDelinquentValuationAllowance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems" xlink:to="pfg_DaysDelinquentValuationAllowance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseAllowanceForCreditLossExcludingAccruedInterest" xlink:label="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseAllowanceForCreditLossExcludingAccruedInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems" xlink:to="pfg_FinancingReceivableAndDirectFinancingLeaseNetInvestmentInLeaseAllowanceForCreditLossExcludingAccruedInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableAccruedInterestWriteoff" xlink:label="us-gaap_FinancingReceivableAccruedInterestWriteoff" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems" xlink:to="us-gaap_FinancingReceivableAccruedInterestWriteoff" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsMortgageLoansDetails" xlink:type="extended" xlink:title="99940411 - Disclosure - Investments - Mortgage Loans (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:label="us-gaap_FinancingReceivablePortfolioSegmentDomain_639069372509247970" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentAxis" xlink:to="us-gaap_FinancingReceivablePortfolioSegmentDomain_639069372509247970" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember" xlink:label="us-gaap_CommercialRealEstatePortfolioSegmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="us-gaap_CommercialRealEstatePortfolioSegmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResidentialMortgageMember" xlink:label="us-gaap_ResidentialMortgageMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancingReceivablePortfolioSegmentDomain" xlink:to="us-gaap_ResidentialMortgageMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:to="srt_StatementGeographicalAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain_639069372509253631" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain_639069372509253631" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NewEnglandMember" xlink:label="pfg_NewEnglandMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_SegmentGeographicalDomain" xlink:to="pfg_NewEnglandMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MiddleAtlanticMember" xlink:label="pfg_MiddleAtlanticMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_SegmentGeographicalDomain" xlink:to="pfg_MiddleAtlanticMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EastNorthCentralMember" xlink:label="pfg_EastNorthCentralMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_SegmentGeographicalDomain" xlink:to="pfg_EastNorthCentralMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_WestNorthCentralMember" xlink:label="pfg_WestNorthCentralMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_SegmentGeographicalDomain" xlink:to="pfg_WestNorthCentralMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SouthAtlanticMember" xlink:label="pfg_SouthAtlanticMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_SegmentGeographicalDomain" xlink:to="pfg_SouthAtlanticMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EastSouthCentralMember" xlink:label="pfg_EastSouthCentralMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="srt_SegmentGeographicalDomain" xlink:to="pfg_EastSouthCentralMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_WestSouthCentralMember" xlink:label="pfg_WestSouthCentralMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="srt_SegmentGeographicalDomain" xlink:to="pfg_WestSouthCentralMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MountainMember" xlink:label="pfg_MountainMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="srt_SegmentGeographicalDomain" xlink:to="pfg_MountainMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PacificMember" xlink:label="pfg_PacificMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="srt_SegmentGeographicalDomain" xlink:to="pfg_PacificMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InternationalMember" xlink:label="pfg_InternationalMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="srt_SegmentGeographicalDomain" xlink:to="pfg_InternationalMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis" xlink:label="srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:to="srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:label="srt_MortgageLoansOnRealEstateNamePropertyTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis" xlink:to="srt_MortgageLoansOnRealEstateNamePropertyTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:label="srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_639069372509317743" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis" xlink:to="srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_639069372509317743" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_OfficeBuildingMember" xlink:label="srt_OfficeBuildingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:to="srt_OfficeBuildingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RetailSiteMember" xlink:label="srt_RetailSiteMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:to="srt_RetailSiteMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_IndustrialPropertyMember" xlink:label="srt_IndustrialPropertyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:to="srt_IndustrialPropertyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ApartmentBuildingMember" xlink:label="srt_ApartmentBuildingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:to="srt_ApartmentBuildingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_HotelMember" xlink:label="srt_HotelMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:to="srt_HotelMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_OtherPropertyMember" xlink:label="srt_OtherPropertyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="srt_MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:to="srt_OtherPropertyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:label="us-gaap_AccountsNotesAndLoansReceivableLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableSignificantPurchases" xlink:label="us-gaap_FinancingReceivableSignificantPurchases" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_FinancingReceivableSignificantPurchases" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableSignificantSales" xlink:label="us-gaap_FinancingReceivableSignificantSales" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_FinancingReceivableSignificantSales" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PercentageOfMortgageLoans" xlink:label="pfg_PercentageOfMortgageLoans" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="pfg_PercentageOfMortgageLoans" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsOtherInvestmentsDetails" xlink:type="extended" xlink:title="99940414 - Disclosure - Investments - Other Investments (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:label="us-gaap_ScheduleOfEquityMethodInvestmentsTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain_639069372509341581" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain_639069372509341581" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EquityMethodInvestmentsNetInvestmentInUnconsolidatedEntitiesMember" xlink:label="pfg_EquityMethodInvestmentsNetInvestmentInUnconsolidatedEntitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="pfg_EquityMethodInvestmentsNetInvestmentInUnconsolidatedEntitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" xlink:label="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:to="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" xlink:label="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" xlink:to="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" xlink:label="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain_639069372509347277" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" xlink:to="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain_639069372509347277" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember" xlink:label="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" xlink:to="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:label="us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:to="us-gaap_ScheduleOfEquityMethodInvestmentsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAbstract" xlink:label="us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:to="us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAbstract" xlink:to="us-gaap_Assets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities" xlink:label="us-gaap_Liabilities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAbstract" xlink:to="us-gaap_Liabilities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAbstract" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityMethodInvestmentUnderlyingEquityInNetAssets" xlink:label="us-gaap_EquityMethodInvestmentUnderlyingEquityInNetAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAbstract" xlink:to="us-gaap_EquityMethodInvestmentUnderlyingEquityInNetAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues" xlink:label="us-gaap_Revenues" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAbstract" xlink:to="us-gaap_Revenues" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAbstract" xlink:to="us-gaap_ProfitLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EquityMethodInvestmentSummarizedFinancialInformationProportionateShareOfNetIncomeLoss" xlink:label="pfg_EquityMethodInvestmentSummarizedFinancialInformationProportionateShareOfNetIncomeLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_EquityMethodInvestmentSummarizedFinancialInformationAbstract" xlink:to="pfg_EquityMethodInvestmentSummarizedFinancialInformationProportionateShareOfNetIncomeLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherTypesOfInvestmentsAbstract" xlink:label="pfg_OtherTypesOfInvestmentsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:to="pfg_OtherTypesOfInvestmentsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashSurrenderValueOfLifeInsurance" xlink:label="us-gaap_CashSurrenderValueOfLifeInsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_OtherTypesOfInvestmentsAbstract" xlink:to="us-gaap_CashSurrenderValueOfLifeInsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CertainSponsoredInvestmentFunds" xlink:label="pfg_CertainSponsoredInvestmentFunds" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_OtherTypesOfInvestmentsAbstract" xlink:to="pfg_CertainSponsoredInvestmentFunds" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsSecuritiesPostedAsCollateralDetails" xlink:type="extended" xlink:title="99940415 - Disclosure - Investments - Securities Posted as Collateral (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralTable" xlink:label="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgedStatusAxis" xlink:label="us-gaap_PledgedStatusAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralTable" xlink:to="us-gaap_PledgedStatusAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgedStatusDomain" xlink:label="us-gaap_PledgedStatusDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PledgedStatusAxis" xlink:to="us-gaap_PledgedStatusDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgedStatusDomain" xlink:label="us-gaap_PledgedStatusDomain_639069372509540067" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PledgedStatusAxis" xlink:to="us-gaap_PledgedStatusDomain_639069372509540067" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetPledgedAsCollateralMember" xlink:label="us-gaap_AssetPledgedAsCollateralMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PledgedStatusDomain" xlink:to="us-gaap_AssetPledgedAsCollateralMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetPledgedAsCollateralWithRightMember" xlink:label="us-gaap_AssetPledgedAsCollateralWithRightMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PledgedStatusDomain" xlink:to="us-gaap_AssetPledgedAsCollateralWithRightMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgingPurposeAxis" xlink:label="us-gaap_PledgingPurposeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralTable" xlink:to="us-gaap_PledgingPurposeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgingPurposeDomain" xlink:label="us-gaap_PledgingPurposeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PledgingPurposeAxis" xlink:to="us-gaap_PledgingPurposeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgingPurposeDomain" xlink:label="us-gaap_PledgingPurposeDomain_639069372509545616" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PledgingPurposeAxis" xlink:to="us-gaap_PledgingPurposeDomain_639069372509545616" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FederalHomeLoanBankAdvancesMember" xlink:label="us-gaap_FederalHomeLoanBankAdvancesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PledgingPurposeDomain" xlink:to="us-gaap_FederalHomeLoanBankAdvancesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralLineItems" xlink:label="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralLineItems" xlink:to="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAbstract" xlink:label="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralLineItems" xlink:to="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" xlink:label="us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAbstract" xlink:to="us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FixedMaturitiesPledgedAsCollateral" xlink:label="pfg_FixedMaturitiesPledgedAsCollateral" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAbstract" xlink:to="pfg_FixedMaturitiesPledgedAsCollateral" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentsOwnedAtFairValue" xlink:label="us-gaap_FinancialInstrumentsOwnedAtFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAbstract" xlink:to="us-gaap_FinancialInstrumentsOwnedAtFairValue" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsBalanceSheetOffsettingAssetsDetails" xlink:type="extended" xlink:title="99940416 - Disclosure - Investments - Balance Sheet Offsetting, Assets (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OffsettingAssetsTable" xlink:label="us-gaap_OffsettingAssetsTable" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialAssetTypeAxis" xlink:label="pfg_FinancialAssetTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_OffsettingAssetsTable" xlink:to="pfg_FinancialAssetTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialAssetTypeCategorizationDomain" xlink:label="pfg_FinancialAssetTypeCategorizationDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="pfg_FinancialAssetTypeAxis" xlink:to="pfg_FinancialAssetTypeCategorizationDomain" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialAssetTypeCategorizationDomain" xlink:label="pfg_FinancialAssetTypeCategorizationDomain_639069372509556767" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="pfg_FinancialAssetTypeAxis" xlink:to="pfg_FinancialAssetTypeCategorizationDomain_639069372509556767" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFinancialInstrumentsAssetsMember" xlink:label="us-gaap_DerivativeFinancialInstrumentsAssetsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_FinancialAssetTypeCategorizationDomain" xlink:to="us-gaap_DerivativeFinancialInstrumentsAssetsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ReverseRepurchaseAgreementMember" xlink:label="pfg_ReverseRepurchaseAgreementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FinancialAssetTypeCategorizationDomain" xlink:to="pfg_ReverseRepurchaseAgreementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OffsettingAssetsLineItems" xlink:label="us-gaap_OffsettingAssetsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_OffsettingAssetsLineItems" xlink:to="us-gaap_OffsettingAssetsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GrossAmountRecognizedAssetsSubjectToNetting" xlink:label="pfg_GrossAmountRecognizedAssetsSubjectToNetting" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_OffsettingAssetsLineItems" xlink:to="pfg_GrossAmountRecognizedAssetsSubjectToNetting" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GrossAmountRecognizedAssetsSubjectToNettingNotOffset" xlink:label="pfg_GrossAmountRecognizedAssetsSubjectToNettingNotOffset" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_OffsettingAssetsLineItems" xlink:to="pfg_GrossAmountRecognizedAssetsSubjectToNettingNotOffset" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CollateralReceivedAssetsSubjectToNettingNotOffset" xlink:label="pfg_CollateralReceivedAssetsSubjectToNettingNotOffset" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_OffsettingAssetsLineItems" xlink:to="pfg_CollateralReceivedAssetsSubjectToNettingNotOffset" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetAmountAssetsSubjectToNetting" xlink:label="pfg_NetAmountAssetsSubjectToNetting" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_OffsettingAssetsLineItems" xlink:to="pfg_NetAmountAssetsSubjectToNetting" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureInvestmentsBalanceSheetOffsettingLiabilitiesDetails" xlink:type="extended" xlink:title="99940417 - Disclosure - Investments - Balance Sheet Offsetting, Liabilities (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OffsettingLiabilitiesTable" xlink:label="us-gaap_OffsettingLiabilitiesTable" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialLiabilityTypeAxis" xlink:label="pfg_FinancialLiabilityTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_OffsettingLiabilitiesTable" xlink:to="pfg_FinancialLiabilityTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialLiabilityTypeCategorizationDomain" xlink:label="pfg_FinancialLiabilityTypeCategorizationDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="pfg_FinancialLiabilityTypeAxis" xlink:to="pfg_FinancialLiabilityTypeCategorizationDomain" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialLiabilityTypeCategorizationDomain" xlink:label="pfg_FinancialLiabilityTypeCategorizationDomain_639069372509562319" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="pfg_FinancialLiabilityTypeAxis" xlink:to="pfg_FinancialLiabilityTypeCategorizationDomain_639069372509562319" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember" xlink:label="us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_FinancialLiabilityTypeCategorizationDomain" xlink:to="us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OffsettingLiabilitiesLineItems" xlink:label="us-gaap_OffsettingLiabilitiesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_OffsettingLiabilitiesLineItems" xlink:to="us-gaap_OffsettingLiabilitiesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GrossAmountRecognizedLiabilitiesSubjectToNetting" xlink:label="pfg_GrossAmountRecognizedLiabilitiesSubjectToNetting" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_OffsettingLiabilitiesLineItems" xlink:to="pfg_GrossAmountRecognizedLiabilitiesSubjectToNetting" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GrossAmountRecognizedLiabilitiesSubjectToNettingNotOffset" xlink:label="pfg_GrossAmountRecognizedLiabilitiesSubjectToNettingNotOffset" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_OffsettingLiabilitiesLineItems" xlink:to="pfg_GrossAmountRecognizedLiabilitiesSubjectToNettingNotOffset" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CollateralPledgedLiabilitiesSubjectToNettingNotOffset" xlink:label="pfg_CollateralPledgedLiabilitiesSubjectToNettingNotOffset" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_OffsettingLiabilitiesLineItems" xlink:to="pfg_CollateralPledgedLiabilitiesSubjectToNettingNotOffset" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetAmountLiabilitiesSubjectToNetting" xlink:label="pfg_NetAmountLiabilitiesSubjectToNetting" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_OffsettingLiabilitiesLineItems" xlink:to="pfg_NetAmountLiabilitiesSubjectToNetting" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountsAndCreditExposureDetails" xlink:type="extended" xlink:title="99940501 - Disclosure - Derivative Financial Instruments - Notional Amounts and Credit Exposure (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeNotionalCreditExposureTable" xlink:label="pfg_DerivativeNotionalCreditExposureTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="us-gaap_DerivativeInstrumentRiskAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_DerivativeNotionalCreditExposureTable" xlink:to="us-gaap_DerivativeInstrumentRiskAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain_639069372509574939" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain_639069372509574939" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateSwapMember" xlink:label="us-gaap_InterestRateSwapMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_InterestRateSwapMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InterestRateOptionsMember" xlink:label="pfg_InterestRateOptionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="pfg_InterestRateOptionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InterestRateForwardsMember" xlink:label="pfg_InterestRateForwardsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="pfg_InterestRateForwardsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InterestRateFutureMember" xlink:label="pfg_InterestRateFutureMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="pfg_InterestRateFutureMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CurrencySwapMember" xlink:label="us-gaap_CurrencySwapMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_CurrencySwapMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeForwardMember" xlink:label="us-gaap_ForeignExchangeForwardMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_ForeignExchangeForwardMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockOptionMember" xlink:label="us-gaap_StockOptionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_StockOptionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SingleStockFutureMember" xlink:label="us-gaap_SingleStockFutureMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_SingleStockFutureMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditDefaultSwapMember" xlink:label="us-gaap_CreditDefaultSwapMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_CreditDefaultSwapMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TotalReturnSwapMember" xlink:label="us-gaap_TotalReturnSwapMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_TotalReturnSwapMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmbeddedDerivativeFinancialInstrumentsMember" xlink:label="us-gaap_EmbeddedDerivativeFinancialInstrumentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_EmbeddedDerivativeFinancialInstrumentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeInstrumentContractAxis" xlink:label="pfg_DerivativeInstrumentContractAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_DerivativeNotionalCreditExposureTable" xlink:to="pfg_DerivativeInstrumentContractAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeInstrumentContractDomain" xlink:label="pfg_DerivativeInstrumentContractDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="pfg_DerivativeInstrumentContractAxis" xlink:to="pfg_DerivativeInstrumentContractDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeInstrumentContractDomain" xlink:label="pfg_DerivativeInstrumentContractDomain_639069372509589614" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="pfg_DerivativeInstrumentContractAxis" xlink:to="pfg_DerivativeInstrumentContractDomain_639069372509589614" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EquityContractsMember" xlink:label="pfg_EquityContractsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_DerivativeInstrumentContractDomain" xlink:to="pfg_EquityContractsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CreditContractsMember" xlink:label="pfg_CreditContractsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_DerivativeInstrumentContractDomain" xlink:to="pfg_CreditContractsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeNotionalCreditExposureLineItems" xlink:label="pfg_DerivativeNotionalCreditExposureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="pfg_DerivativeNotionalCreditExposureTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InterestRateDerivativesCashExchanged" xlink:label="pfg_InterestRateDerivativesCashExchanged" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="pfg_InterestRateDerivativesCashExchanged" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InterestRateDerivativesPrincipalPayments" xlink:label="pfg_InterestRateDerivativesPrincipalPayments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="pfg_InterestRateDerivativesPrincipalPayments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeCollateralPledged" xlink:label="pfg_DerivativeCollateralPledged" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="pfg_DerivativeCollateralPledged" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNetLiabilityPositionAggregateFairValue" xlink:label="us-gaap_DerivativeNetLiabilityPositionAggregateFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="us-gaap_DerivativeNetLiabilityPositionAggregateFairValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralAlreadyPostedAggregateFairValue" xlink:label="us-gaap_CollateralAlreadyPostedAggregateFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="us-gaap_CollateralAlreadyPostedAggregateFairValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalCollateralAggregateFairValue" xlink:label="us-gaap_AdditionalCollateralAggregateFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="us-gaap_AdditionalCollateralAggregateFairValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CashCollateralReceivedAssociatedWithDerivatives" xlink:label="pfg_CashCollateralReceivedAssociatedWithDerivatives" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="pfg_CashCollateralReceivedAssociatedWithDerivatives" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNotionalAmount" xlink:label="us-gaap_DerivativeNotionalAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="us-gaap_DerivativeNotionalAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeCreditExposure" xlink:label="pfg_DerivativeCreditExposure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="pfg_DerivativeCreditExposure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeCollateralReceived" xlink:label="pfg_DerivativeCollateralReceived" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="pfg_DerivativeCollateralReceived" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeNetCreditExposure" xlink:label="pfg_DerivativeNetCreditExposure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="pfg_DerivativeNotionalCreditExposureLineItems" xlink:to="pfg_DerivativeNetCreditExposure" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsFairValueOfDerivativesDetails" xlink:type="extended" xlink:title="99940502 - Disclosure - Derivative Financial Instruments - Fair Value of Derivatives (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:label="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="us-gaap_DerivativeInstrumentRiskAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="us-gaap_DerivativeInstrumentRiskAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain_639069372509623672" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain_639069372509623672" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateContractMember" xlink:label="us-gaap_InterestRateContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_InterestRateContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeContractMember" xlink:label="us-gaap_ForeignExchangeContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_ForeignExchangeContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityContractMember" xlink:label="us-gaap_EquityContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_EquityContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditRiskContractMember" xlink:label="us-gaap_CreditRiskContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_CreditRiskContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherContractMember" xlink:label="us-gaap_OtherContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_OtherContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis" xlink:label="us-gaap_HedgingDesignationAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="us-gaap_HedgingDesignationAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain" xlink:label="us-gaap_HedgingDesignationDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_HedgingDesignationAxis" xlink:to="us-gaap_HedgingDesignationDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain" xlink:label="us-gaap_HedgingDesignationDomain_639069372509635294" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_HedgingDesignationAxis" xlink:to="us-gaap_HedgingDesignationDomain_639069372509635294" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="us-gaap_DesignatedAsHedgingInstrumentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_HedgingDesignationDomain" xlink:to="us-gaap_DesignatedAsHedgingInstrumentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NotDesignatedAsHedgingInstrumentEconomicHedgeMember" xlink:label="us-gaap_NotDesignatedAsHedgingInstrumentEconomicHedgeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_HedgingDesignationDomain" xlink:to="us-gaap_NotDesignatedAsHedgingInstrumentEconomicHedgeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativesFairValueLineItems" xlink:label="us-gaap_DerivativesFairValueLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement" xlink:label="us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeLiabilityFairValueNetLiabilityIncludingNotSubjectToMasterNettingArrangementIncludingFundsWithheldEmbeddedDerivative" xlink:label="pfg_DerivativeLiabilityFairValueNetLiabilityIncludingNotSubjectToMasterNettingArrangementIncludingFundsWithheldEmbeddedDerivative" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="pfg_DerivativeLiabilityFairValueNetLiabilityIncludingNotSubjectToMasterNettingArrangementIncludingFundsWithheldEmbeddedDerivative" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeFairValueOfDerivativeLiabilityInvestmentAndUniversalLifeContracts" xlink:label="pfg_DerivativeFairValueOfDerivativeLiabilityInvestmentAndUniversalLifeContracts" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="pfg_DerivativeFairValueOfDerivativeLiabilityInvestmentAndUniversalLifeContracts" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" xlink:label="us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsCreditDerivativesSoldDetails" xlink:type="extended" xlink:title="99940503 - Disclosure - Derivative Financial Instruments - Credit Derivatives Sold (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfCreditDerivativesTable" xlink:label="us-gaap_ScheduleOfCreditDerivativesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditDerivativesByContractTypeAxis" xlink:label="us-gaap_CreditDerivativesByContractTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfCreditDerivativesTable" xlink:to="us-gaap_CreditDerivativesByContractTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditDerivativesContractTypeDomain" xlink:label="us-gaap_CreditDerivativesContractTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_CreditDerivativesByContractTypeAxis" xlink:to="us-gaap_CreditDerivativesContractTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditDerivativesContractTypeDomain" xlink:label="us-gaap_CreditDerivativesContractTypeDomain_639069372509640847" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_CreditDerivativesByContractTypeAxis" xlink:to="us-gaap_CreditDerivativesContractTypeDomain_639069372509640847" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditDefaultSwapMember" xlink:label="us-gaap_CreditDefaultSwapMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_CreditDerivativesContractTypeDomain" xlink:to="us-gaap_CreditDefaultSwapMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SingleNameCreditDefaultSwapsMember" xlink:label="pfg_SingleNameCreditDefaultSwapsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_CreditDefaultSwapMember" xlink:to="pfg_SingleNameCreditDefaultSwapsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SingleNameTotalReturnSwapsMember" xlink:label="pfg_SingleNameTotalReturnSwapsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_CreditDefaultSwapMember" xlink:to="pfg_SingleNameTotalReturnSwapsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnderlyingAssetClassAxis" xlink:label="us-gaap_UnderlyingAssetClassAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfCreditDerivativesTable" xlink:to="us-gaap_UnderlyingAssetClassAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnderlyingAssetClassDomain" xlink:label="us-gaap_UnderlyingAssetClassDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_UnderlyingAssetClassAxis" xlink:to="us-gaap_UnderlyingAssetClassDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnderlyingAssetClassDomain" xlink:label="us-gaap_UnderlyingAssetClassDomain_639069372509667569" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_UnderlyingAssetClassAxis" xlink:to="us-gaap_UnderlyingAssetClassDomain_639069372509667569" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="us-gaap_CorporateDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_UnderlyingAssetClassDomain" xlink:to="us-gaap_CorporateDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GovernmentDebtMember" xlink:label="pfg_GovernmentDebtMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_UnderlyingAssetClassDomain" xlink:to="pfg_GovernmentDebtMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SovereignDebtMember" xlink:label="us-gaap_SovereignDebtMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_UnderlyingAssetClassDomain" xlink:to="us-gaap_SovereignDebtMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CreditRatingStandardPoorsAxis" xlink:label="srt_CreditRatingStandardPoorsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_ScheduleOfCreditDerivativesTable" xlink:to="srt_CreditRatingStandardPoorsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ExternalCreditRatingStandardPoorsMember" xlink:label="srt_ExternalCreditRatingStandardPoorsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_CreditRatingStandardPoorsAxis" xlink:to="srt_ExternalCreditRatingStandardPoorsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ExternalCreditRatingStandardPoorsMember" xlink:label="srt_ExternalCreditRatingStandardPoorsMember_639069372509667569" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_CreditRatingStandardPoorsAxis" xlink:to="srt_ExternalCreditRatingStandardPoorsMember_639069372509667569" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StandardPoorsAAARatingMember" xlink:label="srt_StandardPoorsAAARatingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ExternalCreditRatingStandardPoorsMember" xlink:to="srt_StandardPoorsAAARatingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StandardPoorsAARatingMember" xlink:label="srt_StandardPoorsAARatingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ExternalCreditRatingStandardPoorsMember" xlink:to="srt_StandardPoorsAARatingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StandardPoorsARatingMember" xlink:label="srt_StandardPoorsARatingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ExternalCreditRatingStandardPoorsMember" xlink:to="srt_StandardPoorsARatingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StandardPoorsBBBRatingMember" xlink:label="srt_StandardPoorsBBBRatingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ExternalCreditRatingStandardPoorsMember" xlink:to="srt_StandardPoorsBBBRatingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditDerivativesLineItems" xlink:label="us-gaap_CreditDerivativesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_CreditDerivativesLineItems" xlink:to="us-gaap_ScheduleOfCreditDerivativesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CreditDerivativeSoldNotional" xlink:label="pfg_CreditDerivativeSoldNotional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_CreditDerivativesLineItems" xlink:to="pfg_CreditDerivativeSoldNotional" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CreditDerivativesSoldFairValue" xlink:label="pfg_CreditDerivativesSoldFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_CreditDerivativesLineItems" xlink:to="pfg_CreditDerivativesSoldFairValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditDerivativeMaximumExposureUndiscounted" xlink:label="us-gaap_CreditDerivativeMaximumExposureUndiscounted" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_CreditDerivativesLineItems" xlink:to="us-gaap_CreditDerivativeMaximumExposureUndiscounted" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CreditDerivativesSoldWeightedAverageExpectedLife" xlink:label="pfg_CreditDerivativesSoldWeightedAverageExpectedLife" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_CreditDerivativesLineItems" xlink:to="pfg_CreditDerivativesSoldWeightedAverageExpectedLife" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsFairValueHedgesDetails" xlink:type="extended" xlink:title="99940504 - Disclosure - Derivative Financial Instruments - Fair Value Hedges (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:label="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="us-gaap_BalanceSheetLocationAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:to="us-gaap_BalanceSheetLocationAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="us-gaap_BalanceSheetLocationDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="us-gaap_BalanceSheetLocationDomain_639069372509667569" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain_639069372509667569" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" xlink:label="pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MortgageLoansMember" xlink:label="pfg_MortgageLoansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="pfg_MortgageLoansMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:to="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:label="us-gaap_SummaryOfFairValueHedgeActivityAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:to="us-gaap_SummaryOfFairValueHedgeActivityAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgedAssetFairValueHedge" xlink:label="us-gaap_HedgedAssetFairValueHedge" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="us-gaap_HedgedAssetFairValueHedge" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgedAssetStatementOfFinancialPositionExtensibleEnumeration" xlink:label="us-gaap_HedgedAssetStatementOfFinancialPositionExtensibleEnumeration" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_HedgedAssetFairValueHedge" xlink:to="us-gaap_HedgedAssetStatementOfFinancialPositionExtensibleEnumeration" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_HedgedAssetDiscontinuedFairValueHedge" xlink:label="pfg_HedgedAssetDiscontinuedFairValueHedge" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="pfg_HedgedAssetDiscontinuedFairValueHedge" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_HedgedAssetFairValueHedgeIncludingDiscontinued" xlink:label="pfg_HedgedAssetFairValueHedgeIncludingDiscontinued" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="pfg_HedgedAssetFairValueHedgeIncludingDiscontinued" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgedAssetFairValueHedgeCumulativeIncreaseDecrease" xlink:label="us-gaap_HedgedAssetFairValueHedgeCumulativeIncreaseDecrease" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="us-gaap_HedgedAssetFairValueHedgeCumulativeIncreaseDecrease" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgedAssetDiscontinuedFairValueHedgeCumulativeIncreaseDecrease" xlink:label="us-gaap_HedgedAssetDiscontinuedFairValueHedgeCumulativeIncreaseDecrease" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="us-gaap_HedgedAssetDiscontinuedFairValueHedgeCumulativeIncreaseDecrease" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_HedgedAssetFairValueHedgeIncludingDiscontinuedCumulativeIncreaseDecrease" xlink:label="pfg_HedgedAssetFairValueHedgeIncludingDiscontinuedCumulativeIncreaseDecrease" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="pfg_HedgedAssetFairValueHedgeIncludingDiscontinuedCumulativeIncreaseDecrease" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgedLiabilityFairValueHedge" xlink:label="us-gaap_HedgedLiabilityFairValueHedge" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="us-gaap_HedgedLiabilityFairValueHedge" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgedLiabilityStatementOfFinancialPositionExtensibleEnumeration" xlink:label="us-gaap_HedgedLiabilityStatementOfFinancialPositionExtensibleEnumeration" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_HedgedLiabilityFairValueHedge" xlink:to="us-gaap_HedgedLiabilityStatementOfFinancialPositionExtensibleEnumeration" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_HedgedLiabilityFairValueHedgeIncludingDiscontinued" xlink:label="pfg_HedgedLiabilityFairValueHedgeIncludingDiscontinued" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="pfg_HedgedLiabilityFairValueHedgeIncludingDiscontinued" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgedLiabilityFairValueHedgeCumulativeIncreaseDecrease" xlink:label="us-gaap_HedgedLiabilityFairValueHedgeCumulativeIncreaseDecrease" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="us-gaap_HedgedLiabilityFairValueHedgeCumulativeIncreaseDecrease" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_HedgedLiabilityFairValueHedgeIncludingDiscontinuedCumulativeIncreaseDecrease" xlink:label="pfg_HedgedLiabilityFairValueHedgeIncludingDiscontinuedCumulativeIncreaseDecrease" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="pfg_HedgedLiabilityFairValueHedgeIncludingDiscontinuedCumulativeIncreaseDecrease" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClosedPortfolioAndBeneficialInterestLastOfLayerAmortizedCost" xlink:label="us-gaap_ClosedPortfolioAndBeneficialInterestLastOfLayerAmortizedCost" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="us-gaap_ClosedPortfolioAndBeneficialInterestLastOfLayerAmortizedCost" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgedAssetFairValueHedgeLastOfLayerCumulativeIncreaseDecrease" xlink:label="us-gaap_HedgedAssetFairValueHedgeLastOfLayerCumulativeIncreaseDecrease" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="us-gaap_HedgedAssetFairValueHedgeLastOfLayerCumulativeIncreaseDecrease" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgedAssetFairValueHedgeLastOfLayerAmount" xlink:label="us-gaap_HedgedAssetFairValueHedgeLastOfLayerAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="us-gaap_HedgedAssetFairValueHedgeLastOfLayerAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossFromComponentsExcludedFromAssessmentOfFairValueHedgeEffectivenessNet" xlink:label="us-gaap_GainLossFromComponentsExcludedFromAssessmentOfFairValueHedgeEffectivenessNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="us-gaap_SummaryOfFairValueHedgeActivityAbstract" xlink:to="us-gaap_GainLossFromComponentsExcludedFromAssessmentOfFairValueHedgeEffectivenessNet" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsCashFlowHedgesDetails" xlink:type="extended" xlink:title="99940505 - Disclosure - Derivative Financial Instruments - Cash Flow Hedges (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:label="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="us-gaap_DerivativeInstrumentRiskAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:to="us-gaap_DerivativeInstrumentRiskAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain_639069372509698221" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain_639069372509698221" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InterestRateContractsFixedMaturitiesAvailableForSaleHedgedMember" xlink:label="pfg_InterestRateContractsFixedMaturitiesAvailableForSaleHedgedMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="pfg_InterestRateContractsFixedMaturitiesAvailableForSaleHedgedMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ForeignExchangeContractsFixedMaturitiesAvailableForSaleHedgedMember" xlink:label="pfg_ForeignExchangeContractsFixedMaturitiesAvailableForSaleHedgedMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="pfg_ForeignExchangeContractsFixedMaturitiesAvailableForSaleHedgedMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InterestRateContractsInvestmentContractsHedgedMember" xlink:label="pfg_InterestRateContractsInvestmentContractsHedgedMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="pfg_InterestRateContractsInvestmentContractsHedgedMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:to="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SummaryOfCashFlowHedgeActivityAbstract" xlink:label="us-gaap_SummaryOfCashFlowHedgeActivityAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:to="us-gaap_SummaryOfCashFlowHedgeActivityAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaximumLengthOfTimeHedgedInCashFlowHedge1" xlink:label="us-gaap_MaximumLengthOfTimeHedgedInCashFlowHedge1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SummaryOfCashFlowHedgeActivityAbstract" xlink:to="us-gaap_MaximumLengthOfTimeHedgedInCashFlowHedge1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AociLossCashFlowHedgeCumulativeGainLoss" xlink:label="pfg_AociLossCashFlowHedgeCumulativeGainLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SummaryOfCashFlowHedgeActivityAbstract" xlink:to="pfg_AociLossCashFlowHedgeCumulativeGainLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SummaryOfCashFlowHedgeActivityAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths" xlink:label="us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SummaryOfCashFlowHedgeActivityAbstract" xlink:to="us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsEffectOfHedgesOnConsolidatedStatementsOfOperationsDetails" xlink:type="extended" xlink:title="99940506 - Disclosure - Derivative Financial Instruments - Effect of Hedges on Consolidated Statements of Operations (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="us-gaap_HedgingRelationshipDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:to="us-gaap_HedgingRelationshipDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="us-gaap_HedgingRelationshipDomain_639069372509723849" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:to="us-gaap_HedgingRelationshipDomain_639069372509723849" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueHedgingMember" xlink:label="us-gaap_FairValueHedgingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_HedgingRelationshipDomain" xlink:to="us-gaap_FairValueHedgingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashFlowHedgingMember" xlink:label="us-gaap_CashFlowHedgingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_HedgingRelationshipDomain" xlink:to="us-gaap_CashFlowHedgingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentHedgingMember" xlink:label="us-gaap_NetInvestmentHedgingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_HedgingRelationshipDomain" xlink:to="us-gaap_NetInvestmentHedgingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="us-gaap_DerivativeInstrumentRiskAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="us-gaap_DerivativeInstrumentRiskAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain_639069372509723849" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain_639069372509723849" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateContractMember" xlink:label="us-gaap_InterestRateContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_InterestRateContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeContractMember" xlink:label="us-gaap_ForeignExchangeContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_ForeignExchangeContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="us-gaap_IncomeStatementLocationAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="us-gaap_IncomeStatementLocationAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain_639069372509723849" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain_639069372509723849" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetInvestmentIncomeLossMember" xlink:label="pfg_NetInvestmentIncomeLossMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="pfg_NetInvestmentIncomeLossMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetRealizedCapitalGainsLossesMember" xlink:label="pfg_NetRealizedCapitalGainsLossesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="pfg_NetRealizedCapitalGainsLossesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_BenefitsClaimsAndSettlementExpensesMember" xlink:label="pfg_BenefitsClaimsAndSettlementExpensesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="pfg_BenefitsClaimsAndSettlementExpensesMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" xlink:label="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:label="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" xlink:to="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:label="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_639069372509723849" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" xlink:to="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_639069372509723849" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember" xlink:label="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:to="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:label="us-gaap_DerivativeInstrumentsGainLossLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:label="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1" xlink:label="us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:to="us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1" xlink:label="us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:to="us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueHedgeIncludedInEffectivenessGainLoss" xlink:label="us-gaap_DerivativeFairValueHedgeIncludedInEffectivenessGainLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:to="us-gaap_DerivativeFairValueHedgeIncludedInEffectivenessGainLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentIncome" xlink:label="us-gaap_NetInvestmentIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:to="us-gaap_NetInvestmentIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnInvestments" xlink:label="us-gaap_GainLossOnInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:to="us-gaap_GainLossOnInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyHolderBenefitsAndClaimIncurredNet" xlink:label="pfg_PolicyHolderBenefitsAndClaimIncurredNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:to="pfg_PolicyHolderBenefitsAndClaimIncurredNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax" xlink:label="us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:to="us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet" xlink:label="us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:to="us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PeriodicSettlementOnDerivatives" xlink:label="pfg_PeriodicSettlementOnDerivatives" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:to="pfg_PeriodicSettlementOnDerivatives" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnDerivativeInstrumentsNetPretax" xlink:label="us-gaap_GainLossOnDerivativeInstrumentsNetPretax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:to="us-gaap_GainLossOnDerivativeInstrumentsNetPretax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDerivativeFinancialInstrumentsDerivativesNotDesignatedAsHedgingInstrumentsDetails" xlink:type="extended" xlink:title="99940507 - Disclosure - Derivative Financial Instruments - Derivatives Not Designated as Hedging Instruments (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="us-gaap_DerivativeInstrumentRiskAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="us-gaap_DerivativeInstrumentRiskAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain_639069372509765440" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain_639069372509765440" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateContractMember" xlink:label="us-gaap_InterestRateContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_InterestRateContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeContractMember" xlink:label="us-gaap_ForeignExchangeContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_ForeignExchangeContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityContractMember" xlink:label="us-gaap_EquityContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_EquityContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditRiskContractMember" xlink:label="us-gaap_CreditRiskContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_CreditRiskContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherContractMember" xlink:label="us-gaap_OtherContractMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_OtherContractMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:label="us-gaap_DerivativeInstrumentsGainLossLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" xlink:label="us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesAdditionalInformationDetails" xlink:type="extended" xlink:title="99940701 - Disclosure - Deferred Acquisition Costs and Other Actuarial Balances - Additional Information (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostTable" xlink:label="us-gaap_DeferredPolicyAcquisitionCostTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DeferredPolicyAcquisitionCostTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372509784975" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372509784975" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LongDurationAndShortDurationInsuranceMember" xlink:label="pfg_LongDurationAndShortDurationInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_LongDurationAndShortDurationInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:label="us-gaap_DeferredPolicyAcquisitionCostLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCostTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" xlink:label="us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesDisaggregatedDacAmountsDetails" xlink:type="extended" xlink:title="99940702 - Disclosure - Deferred Acquisition Costs and Other Actuarial Balances - Disaggregated DAC amounts (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostTable" xlink:label="us-gaap_DeferredPolicyAcquisitionCostTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DeferredPolicyAcquisitionCostTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372509796154" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372509796154" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DeferredPolicyAcquisitionCostTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372509801688" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372509801688" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentSpecialtyBenefitsMember" xlink:label="pfg_SubsegmentSpecialtyBenefitsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentSpecialtyBenefitsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_DeferredPolicyAcquisitionCostTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372509801688" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372509801688" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_WorkplaceSavingsAndRetirementSolutionsMember" xlink:label="pfg_WorkplaceSavingsAndRetirementSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_WorkplaceSavingsAndRetirementSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableAnnuityMember" xlink:label="us-gaap_VariableAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_VariableAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PensionRiskTransferMember" xlink:label="pfg_PensionRiskTransferMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_PensionRiskTransferMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFixedAnnuityMember" xlink:label="us-gaap_DeferredFixedAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_DeferredFixedAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentOnlyMember" xlink:label="pfg_InvestmentOnlyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_InvestmentOnlyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IndividualDisabilityMember" xlink:label="pfg_IndividualDisabilityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_IndividualDisabilityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember" xlink:label="us-gaap_TermLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_TermLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ParticipatingLifeInsurancePolicyMember" xlink:label="us-gaap_ParticipatingLifeInsurancePolicyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_ParticipatingLifeInsurancePolicyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherShortdurationInsuranceProductLineMember" xlink:label="us-gaap_OtherShortdurationInsuranceProductLineMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_OtherShortdurationInsuranceProductLineMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLongdurationInsuranceProductLineMember" xlink:label="us-gaap_OtherLongdurationInsuranceProductLineMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_OtherLongdurationInsuranceProductLineMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:label="us-gaap_DeferredPolicyAcquisitionCostLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCostTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCosts" xlink:label="us-gaap_DeferredPolicyAcquisitionCosts" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCosts" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredPolicyAcquisitionCostsExcludingShortDurationContracts" xlink:label="pfg_DeferredPolicyAcquisitionCostsExcludingShortDurationContracts" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="pfg_DeferredPolicyAcquisitionCostsExcludingShortDurationContracts" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesRetirementAndIncomeSolutionsBalancesAndChangesInDacDetails" xlink:type="extended" xlink:title="99940703 - Disclosure - Deferred Acquisition Costs and Other Actuarial Balances - Retirement and Income Solutions - Balances and changes in DAC (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostTable" xlink:label="us-gaap_DeferredPolicyAcquisitionCostTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DeferredPolicyAcquisitionCostTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372509829662" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372509829662" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_WorkplaceSavingsAndRetirementSolutionsMember" xlink:label="pfg_WorkplaceSavingsAndRetirementSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_WorkplaceSavingsAndRetirementSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableAnnuityMember" xlink:label="us-gaap_VariableAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_VariableAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PensionRiskTransferMember" xlink:label="pfg_PensionRiskTransferMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_PensionRiskTransferMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFixedAnnuityMember" xlink:label="us-gaap_DeferredFixedAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_DeferredFixedAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentOnlyMember" xlink:label="pfg_InvestmentOnlyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_InvestmentOnlyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DeferredPolicyAcquisitionCostTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372509835226" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372509835226" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:label="us-gaap_DeferredPolicyAcquisitionCostLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCostTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCosts" xlink:label="us-gaap_DeferredPolicyAcquisitionCosts" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCosts" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostsAdditions" xlink:label="us-gaap_DeferredPolicyAcquisitionCostsAdditions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCostsAdditions" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" xlink:label="us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesBenefitsAndProtectionBalancesAndChangesInDacDetails" xlink:type="extended" xlink:title="99940704 - Disclosure - Deferred Acquisition Costs and Other Actuarial Balances - Benefits and Protection - Balances and changes in DAC (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostTable" xlink:label="us-gaap_DeferredPolicyAcquisitionCostTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DeferredPolicyAcquisitionCostTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372509846409" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372509846409" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IndividualDisabilityMember" xlink:label="pfg_IndividualDisabilityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_IndividualDisabilityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember" xlink:label="us-gaap_TermLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_TermLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ParticipatingLifeInsurancePolicyMember" xlink:label="us-gaap_ParticipatingLifeInsurancePolicyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_ParticipatingLifeInsurancePolicyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DeferredPolicyAcquisitionCostTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372509851936" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372509851936" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_DeferredPolicyAcquisitionCostTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372509857497" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372509857497" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentSpecialtyBenefitsMember" xlink:label="pfg_SubsegmentSpecialtyBenefitsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentSpecialtyBenefitsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:label="us-gaap_DeferredPolicyAcquisitionCostLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCostTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredPolicyAcquisitionCostsExcludingShortDurationContracts" xlink:label="pfg_DeferredPolicyAcquisitionCostsExcludingShortDurationContracts" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="pfg_DeferredPolicyAcquisitionCostsExcludingShortDurationContracts" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostsAdditions" xlink:label="us-gaap_DeferredPolicyAcquisitionCostsAdditions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCostsAdditions" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" xlink:label="us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DeferredPolicyAcquisitionCostLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesUnearnedRevenueLiabilityDetails" xlink:type="extended" xlink:title="99940705 - Disclosure - Deferred Acquisition Costs and Other Actuarial Balances - Unearned Revenue Liability (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherActuarialBalancesTable" xlink:label="pfg_OtherActuarialBalancesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_OtherActuarialBalancesTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372509868573" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372509868573" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLongdurationInsuranceProductLineMember" xlink:label="us-gaap_OtherLongdurationInsuranceProductLineMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_OtherLongdurationInsuranceProductLineMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_OtherActuarialBalancesTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372509874131" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372509874131" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="pfg_OtherActuarialBalancesTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372509880103" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372509880103" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherActuarialBalancesLineItems" xlink:label="pfg_OtherActuarialBalancesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_OtherActuarialBalancesLineItems" xlink:to="pfg_OtherActuarialBalancesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_UnearnedRevenueLiability" xlink:label="pfg_UnearnedRevenueLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_OtherActuarialBalancesLineItems" xlink:to="pfg_UnearnedRevenueLiability" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDeferredAcquisitionCostsAndOtherActuarialBalancesUnearnedRevenueLiabilityBalancesAndChangesDetails" xlink:type="extended" xlink:title="99940706 - Disclosure - Deferred Acquisition Costs and Other Actuarial Balances - Unearned Revenue Liability Balances and Changes (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherActuarialBalancesTable" xlink:label="pfg_OtherActuarialBalancesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_OtherActuarialBalancesTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372509885679" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372509885679" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_OtherActuarialBalancesTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372509891249" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372509891249" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="pfg_OtherActuarialBalancesTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372509891249" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372509891249" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherActuarialBalancesLineItems" xlink:label="pfg_OtherActuarialBalancesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_OtherActuarialBalancesLineItems" xlink:to="pfg_OtherActuarialBalancesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_UnearnedRevenueLiability" xlink:label="pfg_UnearnedRevenueLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_OtherActuarialBalancesLineItems" xlink:to="pfg_UnearnedRevenueLiability" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_UnearnedRevenueLiabilityDeferrals" xlink:label="pfg_UnearnedRevenueLiabilityDeferrals" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_OtherActuarialBalancesLineItems" xlink:to="pfg_UnearnedRevenueLiabilityDeferrals" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_UnearnedRevenueLiabilityRevenueRecognized" xlink:label="pfg_UnearnedRevenueLiabilityRevenueRecognized" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_OtherActuarialBalancesLineItems" xlink:to="pfg_UnearnedRevenueLiabilityRevenueRecognized" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_UnearnedRevenueLiabilityReinsuranceImpact" xlink:label="pfg_UnearnedRevenueLiabilityReinsuranceImpact" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_OtherActuarialBalancesLineItems" xlink:to="pfg_UnearnedRevenueLiabilityReinsuranceImpact" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_UnearnedRevenueLiabilityAfterReinsurance" xlink:label="pfg_UnearnedRevenueLiabilityAfterReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_OtherActuarialBalancesLineItems" xlink:to="pfg_UnearnedRevenueLiabilityAfterReinsurance" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSeparateAccountBalancesSeparateAccountAssetDetails" xlink:type="extended" xlink:title="99940802 - Disclosure - Separate Account Balances - Separate Account Asset (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentTable" xlink:label="us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountAssetCategoryAxis" xlink:label="us-gaap_SeparateAccountAssetCategoryAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentTable" xlink:to="us-gaap_SeparateAccountAssetCategoryAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountAssetCategoryDomain" xlink:label="us-gaap_SeparateAccountAssetCategoryDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SeparateAccountAssetCategoryAxis" xlink:to="us-gaap_SeparateAccountAssetCategoryDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountAssetCategoryDomain" xlink:label="us-gaap_SeparateAccountAssetCategoryDomain_639069372509954935" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SeparateAccountAssetCategoryAxis" xlink:to="us-gaap_SeparateAccountAssetCategoryDomain_639069372509954935" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountDebtSecurityMember" xlink:label="us-gaap_SeparateAccountDebtSecurityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SeparateAccountAssetCategoryDomain" xlink:to="us-gaap_SeparateAccountDebtSecurityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountEquitySecurityMember" xlink:label="us-gaap_SeparateAccountEquitySecurityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SeparateAccountAssetCategoryDomain" xlink:to="us-gaap_SeparateAccountEquitySecurityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountRealEstateMember" xlink:label="us-gaap_SeparateAccountRealEstateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SeparateAccountAssetCategoryDomain" xlink:to="us-gaap_SeparateAccountRealEstateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeparateAccountOtherInvestmentsMember" xlink:label="pfg_SeparateAccountOtherInvestmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SeparateAccountAssetCategoryDomain" xlink:to="pfg_SeparateAccountOtherInvestmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountCashAndCashEquivalentsMember" xlink:label="us-gaap_SeparateAccountCashAndCashEquivalentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_SeparateAccountAssetCategoryDomain" xlink:to="us-gaap_SeparateAccountCashAndCashEquivalentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeparateAccountOtherAssetsMember" xlink:label="pfg_SeparateAccountOtherAssetsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_SeparateAccountAssetCategoryDomain" xlink:to="pfg_SeparateAccountOtherAssetsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeAxis" xlink:label="us-gaap_InvestmentTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentTable" xlink:to="us-gaap_InvestmentTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember_639069372509966403" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember_639069372509966403" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesMember" xlink:label="us-gaap_DebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_DebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasuryAndGovernmentMember" xlink:label="us-gaap_USTreasuryAndGovernmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_USTreasuryAndGovernmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignGovernmentDebtSecuritiesMember" xlink:label="us-gaap_ForeignGovernmentDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_ForeignGovernmentDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember" xlink:label="us-gaap_USStatesAndPoliticalSubdivisionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_USStatesAndPoliticalSubdivisionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="us-gaap_CorporateDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CorporateDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember" xlink:label="us-gaap_ResidentialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_ResidentialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember" xlink:label="us-gaap_CommercialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CommercialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherDebtSecuritiesMember" xlink:label="us-gaap_OtherDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_OtherDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentLineItems" xlink:label="us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentLineItems" xlink:to="us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentFairValue" xlink:label="us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentLineItems" xlink:to="us-gaap_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentFairValue" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSeparateAccountBalancesSeparateAccountLiabilitiesDetails" xlink:type="extended" xlink:title="99940803 - Disclosure - Separate Account Balances - Separate Account Liabilities (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityTable" xlink:label="us-gaap_SeparateAccountLiabilityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372509984027" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372509984027" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372509989753" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372509989753" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372509995798" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372509995798" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GroupRetirementContractsProductMember" xlink:label="pfg_GroupRetirementContractsProductMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_GroupRetirementContractsProductMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableAnnuityMember" xlink:label="us-gaap_VariableAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_VariableAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PensionMember" xlink:label="pfg_PensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_PensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLongdurationInsuranceProductLineMember" xlink:label="us-gaap_OtherLongdurationInsuranceProductLineMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_OtherLongdurationInsuranceProductLineMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="srt_StatementGeographicalAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain_639069372510007117" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain_639069372510007117" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LatinAmericaMember" xlink:label="srt_LatinAmericaMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_LatinAmericaMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityLineItems" xlink:label="us-gaap_SeparateAccountLiabilityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SeparateAccountLiabilityLineItems" xlink:to="us-gaap_SeparateAccountLiabilityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountsLiability" xlink:label="us-gaap_SeparateAccountsLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SeparateAccountLiabilityLineItems" xlink:to="us-gaap_SeparateAccountsLiability" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSeparateAccountBalancesRetirementAndIncomeSolutionsDetails" xlink:type="extended" xlink:title="99940804 - Disclosure - Separate Account Balances - Retirement and Income Solutions (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityTable" xlink:label="us-gaap_SeparateAccountLiabilityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510018537" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510018537" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510024601" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510024601" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GroupRetirementContractsProductMember" xlink:label="pfg_GroupRetirementContractsProductMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_GroupRetirementContractsProductMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableAnnuityMember" xlink:label="us-gaap_VariableAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_VariableAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityLineItems" xlink:label="us-gaap_SeparateAccountLiabilityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SeparateAccountLiabilityLineItems" xlink:to="us-gaap_SeparateAccountLiabilityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityRollForward" xlink:label="us-gaap_SeparateAccountLiabilityRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SeparateAccountLiabilityLineItems" xlink:to="us-gaap_SeparateAccountLiabilityRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountsLiability" xlink:label="us-gaap_SeparateAccountsLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountsLiability" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityPremiumAndDeposit" xlink:label="us-gaap_SeparateAccountLiabilityPremiumAndDeposit" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountLiabilityPremiumAndDeposit" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityPolicyCharge" xlink:label="us-gaap_SeparateAccountLiabilityPolicyCharge" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountLiabilityPolicyCharge" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeparateAccountLiabilitySurrenderWithdrawalAndBenefitPayment" xlink:label="pfg_SeparateAccountLiabilitySurrenderWithdrawalAndBenefitPayment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="pfg_SeparateAccountLiabilitySurrenderWithdrawalAndBenefitPayment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromInvestedPerformance" xlink:label="us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromInvestedPerformance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromInvestedPerformance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TransferToFromSeparateAccountBalanceToFromGeneralAccount" xlink:label="pfg_TransferToFromSeparateAccountBalanceToFromGeneralAccount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="pfg_TransferToFromSeparateAccountBalanceToFromGeneralAccount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromOtherChange" xlink:label="us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromOtherChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromOtherChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount" xlink:label="us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SeparateAccountLiabilityLineItems" xlink:to="us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSeparateAccountBalancesPrincipalAssetManagementInternationalPensionDetails" xlink:type="extended" xlink:title="99940805 - Disclosure - Separate Account Balances - Principal Asset Management - International Pension (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityTable" xlink:label="us-gaap_SeparateAccountLiabilityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510042663" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510042663" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510048460" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510048460" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510054190" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510054190" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PensionMember" xlink:label="pfg_PensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_PensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="srt_StatementGeographicalAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain_639069372510054190" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain_639069372510054190" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LatinAmericaMember" xlink:label="srt_LatinAmericaMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_LatinAmericaMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityLineItems" xlink:label="us-gaap_SeparateAccountLiabilityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SeparateAccountLiabilityLineItems" xlink:to="us-gaap_SeparateAccountLiabilityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityRollForward" xlink:label="us-gaap_SeparateAccountLiabilityRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SeparateAccountLiabilityLineItems" xlink:to="us-gaap_SeparateAccountLiabilityRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountsLiability" xlink:label="us-gaap_SeparateAccountsLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountsLiability" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityPremiumAndDeposit" xlink:label="us-gaap_SeparateAccountLiabilityPremiumAndDeposit" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountLiabilityPremiumAndDeposit" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityPolicyCharge" xlink:label="us-gaap_SeparateAccountLiabilityPolicyCharge" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountLiabilityPolicyCharge" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeparateAccountLiabilitySurrenderWithdrawalAndBenefitPayment" xlink:label="pfg_SeparateAccountLiabilitySurrenderWithdrawalAndBenefitPayment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="pfg_SeparateAccountLiabilitySurrenderWithdrawalAndBenefitPayment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromInvestedPerformance" xlink:label="us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromInvestedPerformance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromInvestedPerformance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromOtherChange" xlink:label="us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromOtherChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromOtherChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeparateAccountLiabilityIncreaseDecreaseFromForeignCurrencyTranslation" xlink:label="pfg_SeparateAccountLiabilityIncreaseDecreaseFromForeignCurrencyTranslation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="pfg_SeparateAccountLiabilityIncreaseDecreaseFromForeignCurrencyTranslation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount" xlink:label="us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SeparateAccountLiabilityLineItems" xlink:to="us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSeparateAccountBalancesBenefitsAndProtectionDetails" xlink:type="extended" xlink:title="99940806 - Disclosure - Separate Account Balances - Benefits and Protection (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityTable" xlink:label="us-gaap_SeparateAccountLiabilityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510064984" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510064984" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510080815" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510080815" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_SeparateAccountLiabilityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510080815" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510080815" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityLineItems" xlink:label="us-gaap_SeparateAccountLiabilityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SeparateAccountLiabilityLineItems" xlink:to="us-gaap_SeparateAccountLiabilityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityRollForward" xlink:label="us-gaap_SeparateAccountLiabilityRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SeparateAccountLiabilityLineItems" xlink:to="us-gaap_SeparateAccountLiabilityRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountsLiability" xlink:label="us-gaap_SeparateAccountsLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountsLiability" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityPremiumAndDeposit" xlink:label="us-gaap_SeparateAccountLiabilityPremiumAndDeposit" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountLiabilityPremiumAndDeposit" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityPolicyCharge" xlink:label="us-gaap_SeparateAccountLiabilityPolicyCharge" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountLiabilityPolicyCharge" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeparateAccountLiabilitySurrendersWithdrawalAndBenefitPayment" xlink:label="pfg_SeparateAccountLiabilitySurrendersWithdrawalAndBenefitPayment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="pfg_SeparateAccountLiabilitySurrendersWithdrawalAndBenefitPayment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromInvestedPerformance" xlink:label="us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromInvestedPerformance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromInvestedPerformance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TransferToFromSeparateAccountBalanceToFromGeneralAccount" xlink:label="pfg_TransferToFromSeparateAccountBalanceToFromGeneralAccount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_SeparateAccountLiabilityRollForward" xlink:to="pfg_TransferToFromSeparateAccountBalanceToFromGeneralAccount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount" xlink:label="us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SeparateAccountLiabilityLineItems" xlink:to="us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureContractholderFundsDetails" xlink:type="extended" xlink:title="99940901 - Disclosure - Contractholder Funds (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ScheduleOfContractHolderFundsTable" xlink:label="pfg_ScheduleOfContractHolderFundsTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_ScheduleOfContractHolderFundsTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510091047" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510091047" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_ScheduleOfContractHolderFundsTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510091047" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510091047" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="pfg_ScheduleOfContractHolderFundsTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372510091047" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372510091047" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntersegmentEliminationMember" xlink:label="us-gaap_IntersegmentEliminationMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_IntersegmentEliminationMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="pfg_ScheduleOfContractHolderFundsTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510111842" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510111842" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_WorkplaceSavingsAndRetirementSolutionsMember" xlink:label="pfg_WorkplaceSavingsAndRetirementSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_WorkplaceSavingsAndRetirementSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableAnnuityMember" xlink:label="us-gaap_VariableAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_VariableAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFixedAnnuityMember" xlink:label="us-gaap_DeferredFixedAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_DeferredFixedAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ContractHolderFundsLineItems" xlink:label="pfg_ContractHolderFundsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_ContractHolderFundsLineItems" xlink:to="pfg_ScheduleOfContractHolderFundsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderFunds" xlink:label="us-gaap_PolicyholderFunds" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_ContractHolderFundsLineItems" xlink:to="us-gaap_PolicyholderFunds" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ContractHolderFundsReconcilingItemsInvestmentContractsWithoutSignificantFeeRevenue" xlink:label="pfg_ContractHolderFundsReconcilingItemsInvestmentContractsWithoutSignificantFeeRevenue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_ContractHolderFundsLineItems" xlink:to="pfg_ContractHolderFundsReconcilingItemsInvestmentContractsWithoutSignificantFeeRevenue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ContractHolderFundsReconcilingItemsOtherBalances" xlink:label="pfg_ContractHolderFundsReconcilingItemsOtherBalances" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_ContractHolderFundsLineItems" xlink:to="pfg_ContractHolderFundsReconcilingItemsOtherBalances" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ContractholderFunds" xlink:label="pfg_ContractholderFunds" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_ContractHolderFundsLineItems" xlink:to="pfg_ContractholderFunds" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureContractholderFundsGicsAndFundingAgreementsDetails" xlink:type="extended" xlink:title="99940902 - Disclosure - Contractholder Funds - GICs and Funding Agreements (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreementTable" xlink:label="pfg_FundingAgreementTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_FundingAgreementTable" xlink:to="dei_LegalEntityAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_639069372510111842" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_639069372510111842" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PrincipalLifeInsuranceCompanyConsolidatedMember" xlink:label="pfg_PrincipalLifeInsuranceCompanyConsolidatedMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="dei_EntityDomain" xlink:to="pfg_PrincipalLifeInsuranceCompanyConsolidatedMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreementAxis" xlink:label="pfg_FundingAgreementAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_FundingAgreementTable" xlink:to="pfg_FundingAgreementAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreementDomain" xlink:label="pfg_FundingAgreementDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="pfg_FundingAgreementAxis" xlink:to="pfg_FundingAgreementDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreementDomain" xlink:label="pfg_FundingAgreementDomain_639069372510111842" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="pfg_FundingAgreementAxis" xlink:to="pfg_FundingAgreementDomain_639069372510111842" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreementsFederalHomeLoanBankDesMoinesMember" xlink:label="pfg_FundingAgreementsFederalHomeLoanBankDesMoinesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_FundingAgreementDomain" xlink:to="pfg_FundingAgreementsFederalHomeLoanBankDesMoinesMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreement1998ProgramMember" xlink:label="pfg_FundingAgreement1998ProgramMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FundingAgreementDomain" xlink:to="pfg_FundingAgreement1998ProgramMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreement2001ProgramMember" xlink:label="pfg_FundingAgreement2001ProgramMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FundingAgreementDomain" xlink:to="pfg_FundingAgreement2001ProgramMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreement2011ProgramMember" xlink:label="pfg_FundingAgreement2011ProgramMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FundingAgreementDomain" xlink:to="pfg_FundingAgreement2011ProgramMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreementLineItems" xlink:label="pfg_FundingAgreementLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_FundingAgreementLineItems" xlink:to="pfg_FundingAgreementTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreementsProgramsNumber" xlink:label="pfg_FundingAgreementsProgramsNumber" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FundingAgreementLineItems" xlink:to="pfg_FundingAgreementsProgramsNumber" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreementsAuthorizedAmountMaximum" xlink:label="pfg_FundingAgreementsAuthorizedAmountMaximum" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FundingAgreementLineItems" xlink:to="pfg_FundingAgreementsAuthorizedAmountMaximum" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundingAgreements" xlink:label="pfg_FundingAgreements" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FundingAgreementLineItems" xlink:to="pfg_FundingAgreements" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureContractholderFundsChangesInPolicyholderAccountBalancesDetails" xlink:type="extended" xlink:title="99940903 - Disclosure - Contractholder Funds - Changes in Policyholder Account Balances (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceTable" xlink:label="us-gaap_PolicyholderAccountBalanceTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510111842" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510111842" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_PolicyholderAccountBalanceTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510111842" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510111842" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_PolicyholderAccountBalanceTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510111842" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510111842" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_WorkplaceSavingsAndRetirementSolutionsMember" xlink:label="pfg_WorkplaceSavingsAndRetirementSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_WorkplaceSavingsAndRetirementSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableAnnuityMember" xlink:label="us-gaap_VariableAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_VariableAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFixedAnnuityMember" xlink:label="us-gaap_DeferredFixedAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_DeferredFixedAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceLineItems" xlink:label="us-gaap_PolicyholderAccountBalanceLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceLineItems" xlink:to="us-gaap_PolicyholderAccountBalanceTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceRollForward" xlink:label="us-gaap_PolicyholderAccountBalanceRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PolicyholderAccountBalanceLineItems" xlink:to="us-gaap_PolicyholderAccountBalanceRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderFunds" xlink:label="us-gaap_PolicyholderFunds" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="us-gaap_PolicyholderFunds" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalancePremiumReceived" xlink:label="us-gaap_PolicyholderAccountBalancePremiumReceived" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="us-gaap_PolicyholderAccountBalancePremiumReceived" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalancePolicyCharge" xlink:label="us-gaap_PolicyholderAccountBalancePolicyCharge" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="us-gaap_PolicyholderAccountBalancePolicyCharge" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderAccountBalanceSurrenderWithdrawalAndBenefitPayment" xlink:label="pfg_PolicyholderAccountBalanceSurrenderWithdrawalAndBenefitPayment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="pfg_PolicyholderAccountBalanceSurrenderWithdrawalAndBenefitPayment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransferToFromPolicyholderAccountBalanceToFromSeparateAccount" xlink:label="us-gaap_TransferToFromPolicyholderAccountBalanceToFromSeparateAccount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="us-gaap_TransferToFromPolicyholderAccountBalanceToFromSeparateAccount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestCreditedToPolicyholdersAccountBalances" xlink:label="us-gaap_InterestCreditedToPolicyholdersAccountBalances" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="us-gaap_InterestCreditedToPolicyholdersAccountBalances" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet" xlink:label="us-gaap_EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="us-gaap_EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceIncreaseDecreaseFromOtherChange" xlink:label="us-gaap_PolicyholderAccountBalanceIncreaseDecreaseFromOtherChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="us-gaap_PolicyholderAccountBalanceIncreaseDecreaseFromOtherChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderAccountBalanceReinsuranceImpact" xlink:label="pfg_PolicyholderAccountBalanceReinsuranceImpact" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="pfg_PolicyholderAccountBalanceReinsuranceImpact" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderFundsAfterReinsurance" xlink:label="pfg_PolicyholderFundsAfterReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="pfg_PolicyholderFundsAfterReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceWeightedAverageCreditingRate" xlink:label="us-gaap_PolicyholderAccountBalanceWeightedAverageCreditingRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="us-gaap_PolicyholderAccountBalanceWeightedAverageCreditingRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceNetAmountAtRisk" xlink:label="us-gaap_PolicyholderAccountBalanceNetAmountAtRisk" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="us-gaap_PolicyholderAccountBalanceNetAmountAtRisk" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashSurrenderValueDuePolicyholdersAmount" xlink:label="us-gaap_CashSurrenderValueDuePolicyholdersAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_PolicyholderAccountBalanceRollForward" xlink:to="us-gaap_CashSurrenderValueDuePolicyholdersAmount" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureContractholderFundsGuaranteedMinimumInterestRateDetails" xlink:type="extended" xlink:title="99940904 - Disclosure - Contractholder Funds - Guaranteed Minimum Interest Rate (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable" xlink:label="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510167720" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510167720" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_WorkplaceSavingsAndRetirementSolutionsMember" xlink:label="pfg_WorkplaceSavingsAndRetirementSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_WorkplaceSavingsAndRetirementSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableAnnuityMember" xlink:label="us-gaap_VariableAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_VariableAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFixedAnnuityMember" xlink:label="us-gaap_DeferredFixedAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_DeferredFixedAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable" xlink:to="srt_RangeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639069372510167720" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_639069372510167720" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis" xlink:label="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable" xlink:to="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" xlink:label="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis" xlink:to="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" xlink:label="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain_639069372510167720" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis" xlink:to="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain_639069372510167720" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAtGuaranteedMinimumCreditingRateMember" xlink:label="us-gaap_PolicyholderAccountBalanceAtGuaranteedMinimumCreditingRateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" xlink:to="us-gaap_PolicyholderAccountBalanceAtGuaranteedMinimumCreditingRateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0001To0050Member" xlink:label="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0001To0050Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" xlink:to="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0001To0050Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0051To0100Member" xlink:label="pfg_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0051To0100Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" xlink:to="pfg_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0051To0100Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0101To0200Member" xlink:label="pfg_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0101To0200Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" xlink:to="pfg_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0101To0200Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0201AndGreaterMember" xlink:label="pfg_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0201AndGreaterMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain" xlink:to="pfg_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0201AndGreaterMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis" xlink:label="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable" xlink:to="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" xlink:label="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis" xlink:to="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" xlink:label="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain_639069372510167720" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis" xlink:to="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain_639069372510167720" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeUpTo0100Member" xlink:label="pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeUpTo0100Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" xlink:to="pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeUpTo0100Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0101To0200Member" xlink:label="pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0101To0200Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" xlink:to="pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0101To0200Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0201To0300Member" xlink:label="pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0201To0300Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" xlink:to="pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0201To0300Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0301To0400Member" xlink:label="pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0301To0400Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" xlink:to="pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0301To0400Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0401AndGreaterMember" xlink:label="pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0401AndGreaterMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain" xlink:to="pfg_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0401AndGreaterMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="5" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510167720" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510167720" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="6" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510167720" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510167720" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateLineItems" xlink:label="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateLineItems" xlink:to="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderFundsWithGuaranteedMinimumCreditingRate" xlink:label="pfg_PolicyholderFundsWithGuaranteedMinimumCreditingRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateLineItems" xlink:to="pfg_PolicyholderFundsWithGuaranteedMinimumCreditingRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PolicyholderFundsWithoutGuaranteedMinimumCreditingRate" xlink:label="pfg_PolicyholderFundsWithoutGuaranteedMinimumCreditingRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateLineItems" xlink:to="pfg_PolicyholderFundsWithoutGuaranteedMinimumCreditingRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderFunds" xlink:label="us-gaap_PolicyholderFunds" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateLineItems" xlink:to="us-gaap_PolicyholderFunds" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditRating" xlink:label="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditRating" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateLineItems" xlink:to="us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditRating" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsDisaggregatedAmountsIncludedInFuturePolicyBenefitsAndClaimsDetails" xlink:type="extended" xlink:title="99941001 - Disclosure - Future Policy Benefits and Claims - Disaggregated Amounts Included in Future Policy Benefits and Claims (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510167720" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510167720" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentSpecialtyBenefitsMember" xlink:label="pfg_SubsegmentSpecialtyBenefitsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentSpecialtyBenefitsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable" xlink:to="srt_StatementGeographicalAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain_639069372510248013" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain_639069372510248013" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LatinAmericaMember" xlink:label="srt_LatinAmericaMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_LatinAmericaMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510248013" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510248013" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PensionRiskTransferMember" xlink:label="pfg_PensionRiskTransferMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_PensionRiskTransferMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedAnnuityMember" xlink:label="us-gaap_FixedAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_FixedAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IndividualDisabilityMember" xlink:label="pfg_IndividualDisabilityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_IndividualDisabilityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember" xlink:label="us-gaap_TermLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_TermLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LongTermCareInsuranceMember" xlink:label="pfg_LongTermCareInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_LongTermCareInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510248013" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510248013" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefits" xlink:label="us-gaap_LiabilityForFuturePolicyBenefits" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefits" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ParticipatingContractsLiabilityForFuturePolicyBenefitsAndClaims" xlink:label="pfg_ParticipatingContractsLiabilityForFuturePolicyBenefitsAndClaims" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:to="pfg_ParticipatingContractsLiabilityForFuturePolicyBenefitsAndClaims" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ShortDurationLiabilityForFuturePolicyBenefitsAndClaims" xlink:label="pfg_ShortDurationLiabilityForFuturePolicyBenefitsAndClaims" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:to="pfg_ShortDurationLiabilityForFuturePolicyBenefitsAndClaims" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CostOfReinsuranceLiability" xlink:label="pfg_CostOfReinsuranceLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:to="pfg_CostOfReinsuranceLiability" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ReinsuranceRecoverableLiability" xlink:label="pfg_ReinsuranceRecoverableLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:to="pfg_ReinsuranceRecoverableLiability" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherContractsLiabilityForFuturePolicyBenefitsAndClaims" xlink:label="pfg_OtherContractsLiabilityForFuturePolicyBenefitsAndClaims" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:to="pfg_OtherContractsLiabilityForFuturePolicyBenefitsAndClaims" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsClaimsDevelopmentTablesDetails" xlink:type="extended" xlink:title="99941003 - Disclosure - Future Policy Benefits and Claims - Claims Development Tables (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsClaimsDevelopmentTable" xlink:label="us-gaap_ShortdurationInsuranceContractsClaimsDevelopmentTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsClaimsDevelopmentTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510285745" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510285745" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LongTermDisabilityGroupLifeWaiverMember" xlink:label="pfg_LongTermDisabilityGroupLifeWaiverMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_LongTermDisabilityGroupLifeWaiverMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" xlink:label="pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GroupLifeMember" xlink:label="pfg_GroupLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_GroupLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsAccidentYearAxis" xlink:label="us-gaap_ShortdurationInsuranceContractsAccidentYearAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ShortdurationInsuranceContractsClaimsDevelopmentTable" xlink:to="us-gaap_ShortdurationInsuranceContractsAccidentYearAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:label="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearAxis" xlink:to="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:label="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain_639069372510291437" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearAxis" xlink:to="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain_639069372510291437" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsAccidentYear2016Member" xlink:label="us-gaap_ShortdurationInsuranceContractsAccidentYear2016Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:to="us-gaap_ShortdurationInsuranceContractsAccidentYear2016Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationInsuranceContractsAccidentYear2017Member" xlink:label="us-gaap_ShortDurationInsuranceContractsAccidentYear2017Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:to="us-gaap_ShortDurationInsuranceContractsAccidentYear2017Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationInsuranceContractsAccidentYear2018Member" xlink:label="us-gaap_ShortDurationInsuranceContractsAccidentYear2018Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:to="us-gaap_ShortDurationInsuranceContractsAccidentYear2018Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationInsuranceContractAccidentYear2019Member" xlink:label="us-gaap_ShortDurationInsuranceContractAccidentYear2019Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:to="us-gaap_ShortDurationInsuranceContractAccidentYear2019Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationInsuranceContractAccidentYear2020Member" xlink:label="us-gaap_ShortDurationInsuranceContractAccidentYear2020Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:to="us-gaap_ShortDurationInsuranceContractAccidentYear2020Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationInsuranceContractAccidentYear2021Member" xlink:label="us-gaap_ShortDurationInsuranceContractAccidentYear2021Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:to="us-gaap_ShortDurationInsuranceContractAccidentYear2021Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationInsuranceContractAccidentYear2022Member" xlink:label="us-gaap_ShortDurationInsuranceContractAccidentYear2022Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:to="us-gaap_ShortDurationInsuranceContractAccidentYear2022Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationInsuranceContractAccidentYear2023Member" xlink:label="us-gaap_ShortDurationInsuranceContractAccidentYear2023Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:to="us-gaap_ShortDurationInsuranceContractAccidentYear2023Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationInsuranceContractAccidentYear2024Member" xlink:label="us-gaap_ShortDurationInsuranceContractAccidentYear2024Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:to="us-gaap_ShortDurationInsuranceContractAccidentYear2024Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationInsuranceContractAccidentYear2025Member" xlink:label="us-gaap_ShortDurationInsuranceContractAccidentYear2025Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_ShortdurationInsuranceContractsAccidentYearDomain" xlink:to="us-gaap_ShortDurationInsuranceContractAccidentYear2025Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClaimsDevelopmentLineItems" xlink:label="us-gaap_ClaimsDevelopmentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ClaimsDevelopmentLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsClaimsDevelopmentTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet" xlink:label="us-gaap_ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ClaimsDevelopmentLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet" xlink:label="us-gaap_ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ClaimsDevelopmentLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsNumberOfReportedClaims" xlink:label="us-gaap_ShortdurationInsuranceContractsNumberOfReportedClaims" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ClaimsDevelopmentLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsNumberOfReportedClaims" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet" xlink:label="us-gaap_ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ClaimsDevelopmentLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNetNotSeparatelyPresented" xlink:label="us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNetNotSeparatelyPresented" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ClaimsDevelopmentLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNetNotSeparatelyPresented" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet" xlink:label="us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_ClaimsDevelopmentLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsReconciliationOfUnpaidClaimsToLiabilityForUnpaidClaimsTableDetails" xlink:type="extended" xlink:title="99941004 - Disclosure - Future Policy Benefits and Claims - Reconciliation of Unpaid Claims to Liability for Unpaid Claims Table (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTable" xlink:label="us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510314341" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510314341" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LongTermDisabilityGroupLifeWaiverMember" xlink:label="pfg_LongTermDisabilityGroupLifeWaiverMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_LongTermDisabilityGroupLifeWaiverMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" xlink:label="pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GroupLifeMember" xlink:label="pfg_GroupLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_GroupLifeMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityLineItems" xlink:label="us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet" xlink:label="us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ReconciliationOfUnpaidClaimsAbstract" xlink:label="pfg_ReconciliationOfUnpaidClaimsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet" xlink:to="pfg_ReconciliationOfUnpaidClaimsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustmentsShortDurationInsuranceContracts" xlink:label="pfg_ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustmentsShortDurationInsuranceContracts" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_ReconciliationOfUnpaidClaimsAbstract" xlink:to="pfg_ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustmentsShortDurationInsuranceContracts" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount" xlink:label="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_ReconciliationOfUnpaidClaimsAbstract" xlink:to="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseAccumulatedUnallocatedClaimAdjustmentExpense" xlink:label="us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseAccumulatedUnallocatedClaimAdjustmentExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_ReconciliationOfUnpaidClaimsAbstract" xlink:to="us-gaap_ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseAccumulatedUnallocatedClaimAdjustmentExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationContractsDiscountedLiabilitiesAmount" xlink:label="us-gaap_ShortDurationContractsDiscountedLiabilitiesAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_ReconciliationOfUnpaidClaimsAbstract" xlink:to="us-gaap_ShortDurationContractsDiscountedLiabilitiesAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LiabilityForClaimsOtherThanShortDuration" xlink:label="pfg_LiabilityForClaimsOtherThanShortDuration" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_ReconciliationOfUnpaidClaimsAbstract" xlink:to="pfg_LiabilityForClaimsOtherThanShortDuration" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense" xlink:label="us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_ReconciliationOfUnpaidClaimsAbstract" xlink:to="us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsClaimDurationAndPayoutTableDetails" xlink:type="extended" xlink:title="99941005 - Disclosure - Future Policy Benefits and Claims - Claim Duration and Payout Table (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationTable" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510331598" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510331598" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LongTermDisabilityGroupLifeWaiverMember" xlink:label="pfg_LongTermDisabilityGroupLifeWaiverMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_LongTermDisabilityGroupLifeWaiverMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" xlink:label="pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GroupLifeMember" xlink:label="pfg_GroupLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_GroupLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen" xlink:label="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsDiscountingTableDetails" xlink:type="extended" xlink:title="99941006 - Disclosure - Future Policy Benefits and Claims - Discounting Table (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesTable" xlink:label="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510354659" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510354659" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LongTermDisabilityGroupLifeWaiverMember" xlink:label="pfg_LongTermDisabilityGroupLifeWaiverMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_LongTermDisabilityGroupLifeWaiverMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" xlink:label="pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_DentalVisionShortTermDisabilityCriticalIllnessAccidentHospitalIndemnityAndPfmlMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GroupLifeMember" xlink:label="pfg_GroupLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_GroupLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesTable" xlink:to="srt_RangeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639069372510360367" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_639069372510360367" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesLineItems" xlink:label="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationContractsDiscountedLiabilitiesAmount" xlink:label="us-gaap_ShortDurationContractsDiscountedLiabilitiesAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesLineItems" xlink:to="us-gaap_ShortDurationContractsDiscountedLiabilitiesAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationContractsDiscountedLiabilitiesDiscountRate" xlink:label="us-gaap_ShortDurationContractsDiscountedLiabilitiesDiscountRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesLineItems" xlink:to="us-gaap_ShortDurationContractsDiscountedLiabilitiesDiscountRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount" xlink:label="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesInterestAccretion" xlink:label="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesInterestAccretion" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesLineItems" xlink:to="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesInterestAccretion" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortDurationInsuranceContractDiscountedLiabilityInterestAccretionStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" xlink:label="us-gaap_ShortDurationInsuranceContractDiscountedLiabilityInterestAccretionStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShortdurationInsuranceContractsDiscountedLiabilitiesInterestAccretion" xlink:to="us-gaap_ShortDurationInsuranceContractDiscountedLiabilityInterestAccretionStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsGrossPremiumsOrAssessmentsAndInterestAccretionDetails" xlink:type="extended" xlink:title="99941007 - Disclosure - Future Policy Benefits and Claims - Gross Premiums or Assessments and Interest Accretion (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510377552" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510377552" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510383254" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510383254" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentSpecialtyBenefitsMember" xlink:label="pfg_SubsegmentSpecialtyBenefitsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentSpecialtyBenefitsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_StatementGeographicalAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain_639069372510388956" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain_639069372510388956" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LatinAmericaMember" xlink:label="srt_LatinAmericaMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_LatinAmericaMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510388956" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510388956" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PensionRiskTransferMember" xlink:label="pfg_PensionRiskTransferMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_PensionRiskTransferMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedAnnuityMember" xlink:label="us-gaap_FixedAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_FixedAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IndividualDisabilityMember" xlink:label="pfg_IndividualDisabilityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_IndividualDisabilityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember" xlink:label="us-gaap_TermLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_TermLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LongTermCareInsuranceMember" xlink:label="pfg_LongTermCareInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_LongTermCareInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitGrossPremiumIncome" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitGrossPremiumIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitGrossPremiumIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitInterestExpense" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitInterestExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitInterestExpense" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsRetirementAndIncomeSolutionsDetails" xlink:type="extended" xlink:title="99941008 - Disclosure - Future Policy Benefits and Claims - Retirement and Income Solutions (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510412381" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510412381" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510412381" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510412381" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PensionRiskTransferMember" xlink:label="pfg_PensionRiskTransferMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_PensionRiskTransferMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedAnnuityMember" xlink:label="us-gaap_FixedAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_FixedAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" xlink:label="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LiabilityForFuturePolicyBenefitReinsuranceImpact" xlink:label="pfg_LiabilityForFuturePolicyBenefitReinsuranceImpact" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="pfg_LiabilityForFuturePolicyBenefitReinsuranceImpact" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsPrincipalAssetManagementInternationalPensionDetails" xlink:type="extended" xlink:title="99941009 - Disclosure - Future Policy Benefits and Claims - Principal Asset Management - International Pension (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510459060" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510459060" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510465156" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510465156" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_StatementGeographicalAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain_639069372510471244" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain_639069372510471244" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LatinAmericaMember" xlink:label="srt_LatinAmericaMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_LatinAmericaMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510476840" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510476840" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedAnnuityMember" xlink:label="us-gaap_FixedAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_FixedAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" xlink:label="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitForeignCurrencyTranslationAdjustment" xlink:label="pfg_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitForeignCurrencyTranslationAdjustment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="pfg_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitForeignCurrencyTranslationAdjustment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsBenefitsAndProtectionDetails" xlink:type="extended" xlink:title="99941010 - Disclosure - Future Policy Benefits and Claims - Benefits and Protection (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510500147" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510500147" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510506399" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510506399" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentSpecialtyBenefitsMember" xlink:label="pfg_SubsegmentSpecialtyBenefitsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentSpecialtyBenefitsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510512048" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510512048" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IndividualDisabilityMember" xlink:label="pfg_IndividualDisabilityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_IndividualDisabilityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember" xlink:label="us-gaap_TermLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_TermLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeReinsuranceAfterDiscountRateChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeReinsuranceAfterDiscountRateChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeReinsuranceAfterDiscountRateChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociLiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeTax" xlink:label="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeCashFlowAndReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeCashFlowAndReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeCashFlowAndReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseFromCashFlowChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseFromCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseFromCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumInterestIncome" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumInterestIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumInterestIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumNetPremiumCollected" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumNetPremiumCollected" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumNetPremiumCollected" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumIssuance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumIssuance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumIssuance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" xlink:label="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceNetPremiumCollected" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceNetPremiumCollected" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceNetPremiumCollected" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefits" xlink:label="us-gaap_LiabilityForFuturePolicyBenefits" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefits" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LiabilityForFuturePolicyBenefitReinsuranceImpact" xlink:label="pfg_LiabilityForFuturePolicyBenefitReinsuranceImpact" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="pfg_LiabilityForFuturePolicyBenefitReinsuranceImpact" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LiabilityForFuturePolicyBenefitActuarialAssumptions" xlink:label="pfg_LiabilityForFuturePolicyBenefitActuarialAssumptions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="pfg_LiabilityForFuturePolicyBenefitActuarialAssumptions" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeBeforeTaxesNetOfReinsuranceActuarialAssumptions" xlink:label="pfg_IncomeBeforeTaxesNetOfReinsuranceActuarialAssumptions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="pfg_IncomeBeforeTaxesNetOfReinsuranceActuarialAssumptions" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsAdditionalLiabilityForCertainBenefitFeaturesDetails" xlink:type="extended" xlink:title="99941011 - Disclosure - Future Policy Benefits and Claims - Additional Liability for Certain Benefit Features (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510556650" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510556650" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510556650" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510556650" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510556650" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510556650" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeCashFlowAndReinsurance" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeCashFlowAndReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeCashFlowAndReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseFromCashFlowChange" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseFromCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseFromCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceInterestIncomeExpense" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceInterestIncomeExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceInterestIncomeExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceNetPremiumCollected" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceNetPremiumCollected" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceNetPremiumCollected" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceBenefitPayment" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceBenefitPayment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceBenefitPayment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AdditionalLiabilityLongDurationInsuranceReinsuranceImpact" xlink:label="pfg_AdditionalLiabilityLongDurationInsuranceReinsuranceImpact" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="pfg_AdditionalLiabilityLongDurationInsuranceReinsuranceImpact" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceAfterReinsurance" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceAfterReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceAfterReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceWeightedAverageDuration" xlink:label="us-gaap_AdditionalLiabilityLongDurationInsuranceWeightedAverageDuration" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="us-gaap_AdditionalLiabilityLongDurationInsuranceWeightedAverageDuration" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AdditionalLiabilityForCertainBenefitFeaturesActuarialAssumptions" xlink:label="pfg_AdditionalLiabilityForCertainBenefitFeaturesActuarialAssumptions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="pfg_AdditionalLiabilityForCertainBenefitFeaturesActuarialAssumptions" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeBeforeTaxesNetOfReinsuranceActuarialAssumptions" xlink:label="pfg_IncomeBeforeTaxesNetOfReinsuranceActuarialAssumptions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward" xlink:to="pfg_IncomeBeforeTaxesNetOfReinsuranceActuarialAssumptions" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsCorporateDetails" xlink:type="extended" xlink:title="99941012 - Disclosure - Future Policy Benefits and Claims - Corporate (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510572442" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510572442" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510572442" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510572442" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LongTermCareInsuranceMember" xlink:label="pfg_LongTermCareInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_LongTermCareInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeReinsuranceAfterDiscountRateChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeReinsuranceAfterDiscountRateChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeReinsuranceAfterDiscountRateChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociLiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeTax" xlink:label="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeCashFlowAndReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeCashFlowAndReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeCashFlowAndReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseFromCashFlowChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseFromCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseFromCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumInterestIncome" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumInterestIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumInterestIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumNetPremiumCollected" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumNetPremiumCollected" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumNetPremiumCollected" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" xlink:label="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefits" xlink:label="us-gaap_LiabilityForFuturePolicyBenefits" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefits" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LiabilityForFuturePolicyBenefitReinsuranceImpact" xlink:label="pfg_LiabilityForFuturePolicyBenefitReinsuranceImpact" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="pfg_LiabilityForFuturePolicyBenefitReinsuranceImpact" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsExpectedFutureGrossPremiumsAndBenefitPaymentsDetails" xlink:type="extended" xlink:title="99941013 - Disclosure - Future Policy Benefits and Claims - Expected Future Gross Premiums and Benefit Payments (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510603230" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510603230" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510603230" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510603230" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentSpecialtyBenefitsMember" xlink:label="pfg_SubsegmentSpecialtyBenefitsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentSpecialtyBenefitsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_StatementGeographicalAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain_639069372510603230" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain_639069372510603230" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LatinAmericaMember" xlink:label="srt_LatinAmericaMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_LatinAmericaMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510603230" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510603230" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PensionRiskTransferMember" xlink:label="pfg_PensionRiskTransferMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_PensionRiskTransferMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedAnnuityMember" xlink:label="us-gaap_FixedAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_FixedAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IndividualDisabilityMember" xlink:label="pfg_IndividualDisabilityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_IndividualDisabilityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember" xlink:label="us-gaap_TermLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_TermLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LongTermCareInsuranceMember" xlink:label="pfg_LongTermCareInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_LongTermCareInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumDiscountedBeforeReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumDiscountedBeforeReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumDiscountedBeforeReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumUndiscountedBeforeReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumUndiscountedBeforeReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumUndiscountedBeforeReinsurance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitUndiscountedBeforeReinsurance" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitUndiscountedBeforeReinsurance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitUndiscountedBeforeReinsurance" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFuturePolicyBenefitsAndClaimsInterestAccretionAndCurrentDiscountRatesDetails" xlink:type="extended" xlink:title="99941014 - Disclosure - Future Policy Benefits and Claims - Interest Accretion and Current Discount Rates (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510664830" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510664830" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372510670022" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372510670022" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentSpecialtyBenefitsMember" xlink:label="pfg_SubsegmentSpecialtyBenefitsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentSpecialtyBenefitsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_StatementGeographicalAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain_639069372510670022" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain_639069372510670022" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LatinAmericaMember" xlink:label="srt_LatinAmericaMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_LatinAmericaMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510692417" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510692417" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PensionRiskTransferMember" xlink:label="pfg_PensionRiskTransferMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_PensionRiskTransferMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedAnnuityMember" xlink:label="us-gaap_FixedAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_FixedAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IndividualDisabilityMember" xlink:label="pfg_IndividualDisabilityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_IndividualDisabilityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember" xlink:label="us-gaap_UniversalLifeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_UniversalLifeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember" xlink:label="us-gaap_TermLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_TermLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LongTermCareInsuranceMember" xlink:label="pfg_LongTermCareInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_LongTermCareInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitActivityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageInterestAccretionRate" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageInterestAccretionRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageInterestAccretionRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureMarketRiskBenefitsAssetAndLiabilityPositionAndReconciliationDetails" xlink:type="extended" xlink:title="99941101 - Disclosure - Market Risk Benefits - Asset and Liability Position and Reconciliation (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitTable" xlink:label="us-gaap_MarketRiskBenefitTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_MarketRiskBenefitTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510709565" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510709565" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_MarketRiskBenefitTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510715282" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510715282" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableAnnuityMember" xlink:label="us-gaap_VariableAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_VariableAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitLineItems" xlink:label="us-gaap_MarketRiskBenefitLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="us-gaap_MarketRiskBenefitTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitAssetAmount" xlink:label="us-gaap_MarketRiskBenefitAssetAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="us-gaap_MarketRiskBenefitAssetAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitLiabilityAmount" xlink:label="us-gaap_MarketRiskBenefitLiabilityAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="us-gaap_MarketRiskBenefitLiabilityAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitAfterIncreaseDecreaseFromInstrumentSpecificCreditRisk" xlink:label="us-gaap_MarketRiskBenefitAfterIncreaseDecreaseFromInstrumentSpecificCreditRisk" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="us-gaap_MarketRiskBenefitAfterIncreaseDecreaseFromInstrumentSpecificCreditRisk" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureMarketRiskBenefitsNetAssetLiabilityBalancesAndChangesInValuationOfMrbsForIndividualVariableAnnuitiesDetails" xlink:type="extended" xlink:title="99941102 - Disclosure - Market Risk Benefits - Net Asset (Liability) Balances and Changes in Valuation of the MRBs for Individual Variable Annuities (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitTable" xlink:label="us-gaap_MarketRiskBenefitTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_MarketRiskBenefitTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510726717" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510726717" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_MarketRiskBenefitTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510732367" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510732367" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableAnnuityMember" xlink:label="us-gaap_VariableAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_VariableAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitLineItems" xlink:label="us-gaap_MarketRiskBenefitLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="us-gaap_MarketRiskBenefitTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitRollForward" xlink:label="us-gaap_MarketRiskBenefitRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="us-gaap_MarketRiskBenefitRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitAfterIncreaseDecreaseFromInstrumentSpecificCreditRisk" xlink:label="us-gaap_MarketRiskBenefitAfterIncreaseDecreaseFromInstrumentSpecificCreditRisk" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_MarketRiskBenefitRollForward" xlink:to="us-gaap_MarketRiskBenefitAfterIncreaseDecreaseFromInstrumentSpecificCreditRisk" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociMarketRiskBenefitInstrumentSpecificCreditRiskBeforeTax" xlink:label="us-gaap_AociMarketRiskBenefitInstrumentSpecificCreditRiskBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_MarketRiskBenefitRollForward" xlink:to="us-gaap_AociMarketRiskBenefitInstrumentSpecificCreditRiskBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitBeforeReinsuranceAndCumulativeIncreaseDecreaseFromInstrumentSpecificCreditRiskChange" xlink:label="us-gaap_MarketRiskBenefitBeforeReinsuranceAndCumulativeIncreaseDecreaseFromInstrumentSpecificCreditRiskChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_MarketRiskBenefitRollForward" xlink:to="us-gaap_MarketRiskBenefitBeforeReinsuranceAndCumulativeIncreaseDecreaseFromInstrumentSpecificCreditRiskChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitInterestExpense" xlink:label="us-gaap_MarketRiskBenefitInterestExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_MarketRiskBenefitRollForward" xlink:to="us-gaap_MarketRiskBenefitInterestExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitBenefitPayment" xlink:label="us-gaap_MarketRiskBenefitBenefitPayment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_MarketRiskBenefitRollForward" xlink:to="us-gaap_MarketRiskBenefitBenefitPayment" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitIncreaseDecreaseFromInterestRateChange" xlink:label="us-gaap_MarketRiskBenefitIncreaseDecreaseFromInterestRateChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_MarketRiskBenefitRollForward" xlink:to="us-gaap_MarketRiskBenefitIncreaseDecreaseFromInterestRateChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitIncreaseDecreaseFromEquityMarketChange" xlink:label="us-gaap_MarketRiskBenefitIncreaseDecreaseFromEquityMarketChange" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_MarketRiskBenefitRollForward" xlink:to="us-gaap_MarketRiskBenefitIncreaseDecreaseFromEquityMarketChange" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitIncreaseDecreaseFromVolatility" xlink:label="us-gaap_MarketRiskBenefitIncreaseDecreaseFromVolatility" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_MarketRiskBenefitRollForward" xlink:to="us-gaap_MarketRiskBenefitIncreaseDecreaseFromVolatility" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitIncreaseDecreaseFromActualPolicyholderBehaviorDifferentFromExpected" xlink:label="us-gaap_MarketRiskBenefitIncreaseDecreaseFromActualPolicyholderBehaviorDifferentFromExpected" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_MarketRiskBenefitRollForward" xlink:to="us-gaap_MarketRiskBenefitIncreaseDecreaseFromActualPolicyholderBehaviorDifferentFromExpected" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitIncreaseDecreaseFromFutureExpectedPolicyholderBehaviorAssumption" xlink:label="us-gaap_MarketRiskBenefitIncreaseDecreaseFromFutureExpectedPolicyholderBehaviorAssumption" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_MarketRiskBenefitRollForward" xlink:to="us-gaap_MarketRiskBenefitIncreaseDecreaseFromFutureExpectedPolicyholderBehaviorAssumption" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitIncreaseDecreaseFromOtherAssumption" xlink:label="us-gaap_MarketRiskBenefitIncreaseDecreaseFromOtherAssumption" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_MarketRiskBenefitRollForward" xlink:to="us-gaap_MarketRiskBenefitIncreaseDecreaseFromOtherAssumption" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MarketRiskBenefitWeightedAverageAttainedAge" xlink:label="pfg_MarketRiskBenefitWeightedAverageAttainedAge" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="pfg_MarketRiskBenefitWeightedAverageAttainedAge" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitNetAmountAtRisk" xlink:label="us-gaap_MarketRiskBenefitNetAmountAtRisk" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_MarketRiskBenefitLineItems" xlink:to="us-gaap_MarketRiskBenefitNetAmountAtRisk" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureMarketRiskBenefitsUnobservableInputsForFairValueMeasurementDetails" xlink:type="extended" xlink:title="99941104 - Disclosure - Market Risk Benefits - Unobservable Inputs for Fair Value Measurement (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372510755085" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372510755085" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372510760838" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372510760838" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableAnnuityMember" xlink:label="us-gaap_VariableAnnuityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_VariableAnnuityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable" xlink:to="srt_RangeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639069372510760838" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_639069372510760838" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_WeightedAverageMember" xlink:label="srt_WeightedAverageMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_RangeMember" xlink:to="srt_WeightedAverageMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeAxis" xlink:label="us-gaap_MeasurementInputTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable" xlink:to="us-gaap_MeasurementInputTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="us-gaap_MeasurementInputTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_MeasurementInputTypeAxis" xlink:to="us-gaap_MeasurementInputTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="us-gaap_MeasurementInputTypeDomain_639069372510772149" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_MeasurementInputTypeAxis" xlink:to="us-gaap_MeasurementInputTypeDomain_639069372510772149" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MeasurementInputLongDurationInterestRateMember" xlink:label="pfg_MeasurementInputLongDurationInterestRateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="pfg_MeasurementInputLongDurationInterestRateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputPriceVolatilityMember" xlink:label="us-gaap_MeasurementInputPriceVolatilityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="us-gaap_MeasurementInputPriceVolatilityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MeasurementInputNonPerformanceRiskMember" xlink:label="pfg_MeasurementInputNonPerformanceRiskMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="pfg_MeasurementInputNonPerformanceRiskMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputLapseRateMember" xlink:label="us-gaap_MeasurementInputLapseRateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="us-gaap_MeasurementInputLapseRateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems" xlink:to="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitMeasurementInput" xlink:label="us-gaap_MarketRiskBenefitMeasurementInput" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems" xlink:to="us-gaap_MarketRiskBenefitMeasurementInput" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureReinsuranceDetails" xlink:type="extended" xlink:title="99941201 - Disclosure - Reinsurance (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededCreditRiskTable" xlink:label="us-gaap_CededCreditRiskTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="us-gaap_ConcentrationRiskByTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_CededCreditRiskTable" xlink:to="us-gaap_ConcentrationRiskByTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="us-gaap_ConcentrationRiskTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_ConcentrationRiskByTypeAxis" xlink:to="us-gaap_ConcentrationRiskTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="us-gaap_ConcentrationRiskTypeDomain_639069372510783581" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_ConcentrationRiskByTypeAxis" xlink:to="us-gaap_ConcentrationRiskTypeDomain_639069372510783581" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsurerConcentrationRiskMember" xlink:label="us-gaap_ReinsurerConcentrationRiskMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ConcentrationRiskTypeDomain" xlink:to="us-gaap_ReinsurerConcentrationRiskMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_CededCreditRiskTable" xlink:to="us-gaap_ConcentrationRiskByBenchmarkAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_639069372510789295" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain_639069372510789295" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetCededReinsuranceRecoverablesMember" xlink:label="pfg_NetCededReinsuranceRecoverablesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="pfg_NetCededReinsuranceRecoverablesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededCreditRiskAxis" xlink:label="us-gaap_CededCreditRiskAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_CededCreditRiskTable" xlink:to="us-gaap_CededCreditRiskAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededCreditRiskReinsurerDomain" xlink:label="us-gaap_CededCreditRiskReinsurerDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_CededCreditRiskAxis" xlink:to="us-gaap_CededCreditRiskReinsurerDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededCreditRiskReinsurerDomain" xlink:label="us-gaap_CededCreditRiskReinsurerDomain_639069372510789295" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_CededCreditRiskAxis" xlink:to="us-gaap_CededCreditRiskReinsurerDomain_639069372510789295" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FiveLargestCededReinsurersMember" xlink:label="pfg_FiveLargestCededReinsurersMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_CededCreditRiskReinsurerDomain" xlink:to="pfg_FiveLargestCededReinsurersMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededCreditRiskLineItems" xlink:label="us-gaap_CededCreditRiskLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_CededCreditRiskLineItems" xlink:to="us-gaap_CededCreditRiskTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsuranceRecoverables" xlink:label="us-gaap_ReinsuranceRecoverables" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_CededCreditRiskLineItems" xlink:to="us-gaap_ReinsuranceRecoverables" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsurancePayable" xlink:label="us-gaap_ReinsurancePayable" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_CededCreditRiskLineItems" xlink:to="us-gaap_ReinsurancePayable" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetCededReinsuranceRecoverables" xlink:label="pfg_NetCededReinsuranceRecoverables" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_CededCreditRiskLineItems" xlink:to="pfg_NetCededReinsuranceRecoverables" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="us-gaap_ConcentrationRiskPercentage1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_CededCreditRiskLineItems" xlink:to="us-gaap_ConcentrationRiskPercentage1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ReinsuranceRecoverablesClaimsReceivedNumbersOfLargestCededReinsurers" xlink:label="pfg_ReinsuranceRecoverablesClaimsReceivedNumbersOfLargestCededReinsurers" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_CededCreditRiskLineItems" xlink:to="pfg_ReinsuranceRecoverablesClaimsReceivedNumbersOfLargestCededReinsurers" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ReinsuranceDepositReceivable" xlink:label="pfg_ReinsuranceDepositReceivable" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_CededCreditRiskLineItems" xlink:to="pfg_ReinsuranceDepositReceivable" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureReinsuranceFundsWithheldDetails" xlink:type="extended" xlink:title="99941204 - Disclosure - Reinsurance - Funds Withheld (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain_639069372510806338" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain_639069372510806338" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" xlink:label="pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FixedMaturitiesTradingMember" xlink:label="pfg_FixedMaturitiesTradingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_FixedMaturitiesTradingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesMember" xlink:label="us-gaap_EquitySecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="us-gaap_EquitySecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MortgageLoansMember" xlink:label="pfg_MortgageLoansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_MortgageLoansMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherInvestmentsMember" xlink:label="us-gaap_OtherInvestmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="us-gaap_OtherInvestmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AssetsCashAndCashEquivalentsMember" xlink:label="pfg_AssetsCashAndCashEquivalentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_AssetsCashAndCashEquivalentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AccruedInterestIncomeReceivableMember" xlink:label="pfg_AccruedInterestIncomeReceivableMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_AccruedInterestIncomeReceivableMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetOtherAssetsAndLiabilitiesMember" xlink:label="pfg_NetOtherAssetsAndLiabilitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_NetOtherAssetsAndLiabilitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FundsHeldUnderReinsuranceAgreementsAsset" xlink:label="us-gaap_FundsHeldUnderReinsuranceAgreementsAsset" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="us-gaap_FundsHeldUnderReinsuranceAgreementsAsset" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FundsHeldUnderReinsuranceAgreementsLiability" xlink:label="us-gaap_FundsHeldUnderReinsuranceAgreementsLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="us-gaap_FundsHeldUnderReinsuranceAgreementsLiability" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsNetOtherAssetLiability" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsNetOtherAssetLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsNetOtherAssetLiability" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EmbeddedDerivativeAsset" xlink:label="pfg_EmbeddedDerivativeAsset" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="pfg_EmbeddedDerivativeAsset" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivative" xlink:label="pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivative" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivative" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureReinsuranceComponentsOfNetInvestmentIncomeOnFundsWithheldAssetsDetails" xlink:type="extended" xlink:title="99941205 - Disclosure - Reinsurance - Components of Net Investment Income on Funds Withheld Assets (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain_639069372510823311" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain_639069372510823311" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" xlink:label="pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FixedMaturitiesTradingMember" xlink:label="pfg_FixedMaturitiesTradingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_FixedMaturitiesTradingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesMember" xlink:label="us-gaap_EquitySecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="us-gaap_EquitySecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MortgageLoansMember" xlink:label="pfg_MortgageLoansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_MortgageLoansMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AssetsCashAndCashEquivalentsMember" xlink:label="pfg_AssetsCashAndCashEquivalentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_AssetsCashAndCashEquivalentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherInvestmentsMember" xlink:label="us-gaap_OtherInvestmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="us-gaap_OtherInvestmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GrossInvestmentIncomeLossOnFundsWithheldAssets" xlink:label="pfg_GrossInvestmentIncomeLossOnFundsWithheldAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="pfg_GrossInvestmentIncomeLossOnFundsWithheldAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentIncomeInvestmentExpenseOnFundsWithheldAssets" xlink:label="pfg_InvestmentIncomeInvestmentExpenseOnFundsWithheldAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="pfg_InvestmentIncomeInvestmentExpenseOnFundsWithheldAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetInvestmentIncomeOnFundsWithheldAssets" xlink:label="pfg_NetInvestmentIncomeOnFundsWithheldAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="pfg_NetInvestmentIncomeOnFundsWithheldAssets" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureReinsuranceComponentsOfNetRealizedCapitalGainsLossesOnFundsWithheldAssetsDetails" xlink:type="extended" xlink:title="99941206 - Disclosure - Reinsurance - Components of Net Realized Capital Gains (Losses) on Funds Withheld Assets (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain_639069372510834664" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetAxis" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain_639069372510834664" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" xlink:label="pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_FixedMaturitiesSecuritiesAvailableForSaleMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FixedMaturitiesTradingMember" xlink:label="pfg_FixedMaturitiesTradingMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_FixedMaturitiesTradingMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesMember" xlink:label="us-gaap_EquitySecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="us-gaap_EquitySecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MortgageLoansMember" xlink:label="pfg_MortgageLoansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="pfg_MortgageLoansMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherInvestmentsMember" xlink:label="us-gaap_OtherInvestmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="us-gaap_OtherInvestmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeMember" xlink:label="us-gaap_DerivativeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetDomain" xlink:to="us-gaap_DerivativeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsAssetTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsHeldUnderReinsuranceAgreementsRealizedCapitalGainsLossesOnAsset" xlink:label="pfg_FundsHeldUnderReinsuranceAgreementsRealizedCapitalGainsLossesOnAsset" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FundsHeldUnderReinsuranceAgreementsAssetLineItems" xlink:to="pfg_FundsHeldUnderReinsuranceAgreementsRealizedCapitalGainsLossesOnAsset" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDebtShortTermDebtDetails" xlink:type="extended" xlink:title="99941301 - Disclosure - Debt - Short-Term Debt (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShortTermDebtTable" xlink:label="us-gaap_ScheduleOfShortTermDebtTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="us-gaap_ShortTermDebtTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfShortTermDebtTable" xlink:to="us-gaap_ShortTermDebtTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="us-gaap_ShortTermDebtTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_ShortTermDebtTypeAxis" xlink:to="us-gaap_ShortTermDebtTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="us-gaap_ShortTermDebtTypeDomain_639069372510845972" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_ShortTermDebtTypeAxis" xlink:to="us-gaap_ShortTermDebtTypeDomain_639069372510845972" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CreditFacilityMaturingOctober2027Member" xlink:label="pfg_CreditFacilityMaturingOctober2027Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="pfg_CreditFacilityMaturingOctober2027Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_UnsecuredLineOfCreditMember" xlink:label="pfg_UnsecuredLineOfCreditMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="pfg_UnsecuredLineOfCreditMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SecuredSubscriptionFacilityMember" xlink:label="pfg_SecuredSubscriptionFacilityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="pfg_SecuredSubscriptionFacilityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialPaperMember" xlink:label="us-gaap_CommercialPaperMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="us-gaap_CommercialPaperMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ParentAndSubsidiariesShelfRegistrationDebtGuarantorAxis" xlink:label="pfg_ParentAndSubsidiariesShelfRegistrationDebtGuarantorAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfShortTermDebtTable" xlink:to="pfg_ParentAndSubsidiariesShelfRegistrationDebtGuarantorAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EntityShelfRegistrationDebtGuarantorDomain" xlink:label="pfg_EntityShelfRegistrationDebtGuarantorDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="pfg_ParentAndSubsidiariesShelfRegistrationDebtGuarantorAxis" xlink:to="pfg_EntityShelfRegistrationDebtGuarantorDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EntityShelfRegistrationDebtGuarantorDomain" xlink:label="pfg_EntityShelfRegistrationDebtGuarantorDomain_639069372510851666" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="pfg_ParentAndSubsidiariesShelfRegistrationDebtGuarantorAxis" xlink:to="pfg_EntityShelfRegistrationDebtGuarantorDomain_639069372510851666" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PrincipalLifeInsuranceCompanyConsolidatedMember" xlink:label="pfg_PrincipalLifeInsuranceCompanyConsolidatedMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_EntityShelfRegistrationDebtGuarantorDomain" xlink:to="pfg_PrincipalLifeInsuranceCompanyConsolidatedMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PrincipalCompaniaDeSegurosDeVidaChileS.a.Member" xlink:label="pfg_PrincipalCompaniaDeSegurosDeVidaChileS.a.Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_EntityShelfRegistrationDebtGuarantorDomain" xlink:to="pfg_PrincipalCompaniaDeSegurosDeVidaChileS.a.Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PrincipalInternationalDeChileS.a.Member" xlink:label="pfg_PrincipalInternationalDeChileS.a.Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_EntityShelfRegistrationDebtGuarantorDomain" xlink:to="pfg_PrincipalInternationalDeChileS.a.Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PrincipalCreditRealEstateIncomeTrustMember" xlink:label="pfg_PrincipalCreditRealEstateIncomeTrustMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_EntityShelfRegistrationDebtGuarantorDomain" xlink:to="pfg_PrincipalCreditRealEstateIncomeTrustMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtLineItems" xlink:label="us-gaap_ShortTermDebtLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ShortTermDebtLineItems" xlink:to="us-gaap_ScheduleOfShortTermDebtTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShortTermDebtLineItems" xlink:to="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermBorrowings" xlink:label="us-gaap_ShortTermBorrowings" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShortTermDebtLineItems" xlink:to="us-gaap_ShortTermBorrowings" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_BackStopFacilitySupportForCommercialPaperProgramPercent" xlink:label="pfg_BackStopFacilitySupportForCommercialPaperProgramPercent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShortTermDebtLineItems" xlink:to="pfg_BackStopFacilitySupportForCommercialPaperProgramPercent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_BackStopFacilityOutstandingBalances" xlink:label="pfg_BackStopFacilityOutstandingBalances" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ShortTermDebtLineItems" xlink:to="pfg_BackStopFacilityOutstandingBalances" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtWeightedAverageInterestRate" xlink:label="us-gaap_ShortTermDebtWeightedAverageInterestRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ShortTermDebtLineItems" xlink:to="us-gaap_ShortTermDebtWeightedAverageInterestRate" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDebtComponentsOfLongTermDebtDetails" xlink:type="extended" xlink:title="99941302 - Disclosure - Debt - Components of Long-Term Debt (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable" xlink:label="us-gaap_DebtInstrumentTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain_639069372510868115" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain_639069372510868115" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable3.125PercentDue2023Member" xlink:label="pfg_NotesPayable3.125PercentDue2023Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable3.125PercentDue2023Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable3.4PercentDue2025Member" xlink:label="pfg_NotesPayable3.4PercentDue2025Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable3.4PercentDue2025Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable3.1PercentDue2026Member" xlink:label="pfg_NotesPayable3.1PercentDue2026Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable3.1PercentDue2026Member" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable4.111PercentDue2028Member" xlink:label="pfg_NotesPayable4.111PercentDue2028Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable4.111PercentDue2028Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable3.7PercentDue2029Member" xlink:label="pfg_NotesPayable3.7PercentDue2029Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable3.7PercentDue2029Member" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable2.125PercentDue2030Member" xlink:label="pfg_NotesPayable2.125PercentDue2030Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable2.125PercentDue2030Member" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable5.375PercentDue2033Member" xlink:label="pfg_NotesPayable5.375PercentDue2033Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable5.375PercentDue2033Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable6.05PercentDue2036Member" xlink:label="pfg_NotesPayable6.05PercentDue2036Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable6.05PercentDue2036Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable4.625PercentDue2042Member" xlink:label="pfg_NotesPayable4.625PercentDue2042Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable4.625PercentDue2042Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable4.35PercentDue2043Member" xlink:label="pfg_NotesPayable4.35PercentDue2043Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable4.35PercentDue2043Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable4.3PercentDue2046Member" xlink:label="pfg_NotesPayable4.3PercentDue2046Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable4.3PercentDue2046Member" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable5.5PercentDue2053Member" xlink:label="pfg_NotesPayable5.5PercentDue2053Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable5.5PercentDue2053Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SecuredCreditFacilitiesMember" xlink:label="pfg_SecuredCreditFacilitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_SecuredCreditFacilitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MortgagesAndNotesPayableMember" xlink:label="pfg_MortgagesAndNotesPayableMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_MortgagesAndNotesPayableMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RecourseStatusAxis" xlink:label="us-gaap_RecourseStatusAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_RecourseStatusAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RecourseStatusDomain" xlink:label="us-gaap_RecourseStatusDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RecourseStatusAxis" xlink:to="us-gaap_RecourseStatusDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RecourseStatusDomain" xlink:label="us-gaap_RecourseStatusDomain_639069372510879367" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RecourseStatusAxis" xlink:to="us-gaap_RecourseStatusDomain_639069372510879367" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonrecourseMember" xlink:label="us-gaap_NonrecourseMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RecourseStatusDomain" xlink:to="us-gaap_NonrecourseMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="us-gaap_DebtInstrumentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="us-gaap_DebtInstrumentCarryingAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentCarryingAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:label="us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt" xlink:label="us-gaap_LongTermDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LongTermDebt" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDebtSeniorNotesAndJuniorSubordinatedNotesDetails" xlink:type="extended" xlink:title="99941303 - Disclosure - Debt - Senior Notes and Junior Subordinated Notes (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable" xlink:label="us-gaap_DebtInstrumentTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain_639069372510897443" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain_639069372510897443" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable3.1PercentDue2026AndNotesPayable4.3PercentDue2046Member" xlink:label="pfg_NotesPayable3.1PercentDue2026AndNotesPayable4.3PercentDue2046Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable3.1PercentDue2026AndNotesPayable4.3PercentDue2046Member" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable3.1PercentDue2026Member" xlink:label="pfg_NotesPayable3.1PercentDue2026Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_NotesPayable3.1PercentDue2026AndNotesPayable4.3PercentDue2046Member" xlink:to="pfg_NotesPayable3.1PercentDue2026Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable4.3PercentDue2046Member" xlink:label="pfg_NotesPayable4.3PercentDue2046Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_NotesPayable3.1PercentDue2026AndNotesPayable4.3PercentDue2046Member" xlink:to="pfg_NotesPayable4.3PercentDue2046Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable3.4PercentDue2025Member" xlink:label="pfg_NotesPayable3.4PercentDue2025Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable3.4PercentDue2025Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable3.7PercentDue2029Member" xlink:label="pfg_NotesPayable3.7PercentDue2029Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable3.7PercentDue2029Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable5.5PercentDue2053Member" xlink:label="pfg_NotesPayable5.5PercentDue2053Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable5.5PercentDue2053Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable1.85PercentDue2017And3.125PercentDue2023And4.35PercentDue2043Member" xlink:label="pfg_NotesPayable1.85PercentDue2017And3.125PercentDue2023And4.35PercentDue2043Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable1.85PercentDue2017And3.125PercentDue2023And4.35PercentDue2043Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable3.125PercentDue2023Member" xlink:label="pfg_NotesPayable3.125PercentDue2023Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_NotesPayable1.85PercentDue2017And3.125PercentDue2023And4.35PercentDue2043Member" xlink:to="pfg_NotesPayable3.125PercentDue2023Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable4.35PercentDue2043Member" xlink:label="pfg_NotesPayable4.35PercentDue2043Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_NotesPayable1.85PercentDue2017And3.125PercentDue2023And4.35PercentDue2043Member" xlink:to="pfg_NotesPayable4.35PercentDue2043Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable5.375PercentDue2033Member" xlink:label="pfg_NotesPayable5.375PercentDue2033Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable5.375PercentDue2033Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable3.3PercentDue2022And4.625PercentDue2042Member" xlink:label="pfg_NotesPayable3.3PercentDue2022And4.625PercentDue2042Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable3.3PercentDue2022And4.625PercentDue2042Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable4.625PercentDue2042Member" xlink:label="pfg_NotesPayable4.625PercentDue2042Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_NotesPayable3.3PercentDue2022And4.625PercentDue2042Member" xlink:to="pfg_NotesPayable4.625PercentDue2042Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable7.875PercentDue2014And8.875PercentDue2019Member" xlink:label="pfg_NotesPayable7.875PercentDue2014And8.875PercentDue2019Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable7.875PercentDue2014And8.875PercentDue2019Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable7.875PercentDue2014Member" xlink:label="pfg_NotesPayable7.875PercentDue2014Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_NotesPayable7.875PercentDue2014And8.875PercentDue2019Member" xlink:to="pfg_NotesPayable7.875PercentDue2014Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable6.05PercentDue2036Member" xlink:label="pfg_NotesPayable6.05PercentDue2036Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable6.05PercentDue2036Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable6.05PercentDue2036IssuedOctober2006Member" xlink:label="pfg_NotesPayable6.05PercentDue2036IssuedOctober2006Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_NotesPayable6.05PercentDue2036Member" xlink:to="pfg_NotesPayable6.05PercentDue2036IssuedOctober2006Member" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable6.05PercentDue2036IssuedDecember2006Member" xlink:label="pfg_NotesPayable6.05PercentDue2036IssuedDecember2006Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_NotesPayable6.05PercentDue2036Member" xlink:to="pfg_NotesPayable6.05PercentDue2036IssuedDecember2006Member" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable2.125PercentDue2030Member" xlink:label="pfg_NotesPayable2.125PercentDue2030Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable2.125PercentDue2030Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SecuredCreditFacilitiesMember" xlink:label="pfg_SecuredCreditFacilitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_SecuredCreditFacilitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="us-gaap_LongtermDebtTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_LongtermDebtTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="us-gaap_LongtermDebtTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="us-gaap_LongtermDebtTypeDomain_639069372510954094" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain_639069372510954094" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember" xlink:label="us-gaap_SeniorNotesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="us-gaap_SeniorNotesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgedStatusAxis" xlink:label="us-gaap_PledgedStatusAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_PledgedStatusAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgedStatusDomain" xlink:label="us-gaap_PledgedStatusDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PledgedStatusAxis" xlink:to="us-gaap_PledgedStatusDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgedStatusDomain" xlink:label="us-gaap_PledgedStatusDomain_639069372510959764" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PledgedStatusAxis" xlink:to="us-gaap_PledgedStatusDomain_639069372510959764" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetPledgedAsCollateralMember" xlink:label="us-gaap_AssetPledgedAsCollateralMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PledgedStatusDomain" xlink:to="us-gaap_AssetPledgedAsCollateralMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="us-gaap_DebtInstrumentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="us-gaap_DebtInstrumentFaceAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentFaceAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="us-gaap_RepaymentsOfLongTermDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_RepaymentsOfLongTermDebt" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt" xlink:label="us-gaap_LongTermDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LongTermDebt" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RealEstateInvestments" xlink:label="us-gaap_RealEstateInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_RealEstateInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentsInRealEstate" xlink:label="pfg_InvestmentsInRealEstate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="pfg_InvestmentsInRealEstate" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDebtNonRecourseMortgagesAndNotesPayableDetails" xlink:type="extended" xlink:title="99941304 - Disclosure - Debt - Non-Recourse Mortgages and Notes Payable (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable" xlink:label="us-gaap_DebtInstrumentTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain_639069372510982374" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain_639069372510982374" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MortgagesAndNotesPayableMember" xlink:label="pfg_MortgagesAndNotesPayableMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_MortgagesAndNotesPayableMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RecourseStatusAxis" xlink:label="us-gaap_RecourseStatusAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_RecourseStatusAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RecourseStatusDomain" xlink:label="us-gaap_RecourseStatusDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RecourseStatusAxis" xlink:to="us-gaap_RecourseStatusDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RecourseStatusDomain" xlink:label="us-gaap_RecourseStatusDomain_639069372510982374" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RecourseStatusAxis" xlink:to="us-gaap_RecourseStatusDomain_639069372510982374" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonrecourseMember" xlink:label="us-gaap_NonrecourseMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RecourseStatusDomain" xlink:to="us-gaap_NonrecourseMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgedStatusAxis" xlink:label="us-gaap_PledgedStatusAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_PledgedStatusAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgedStatusDomain" xlink:label="us-gaap_PledgedStatusDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PledgedStatusAxis" xlink:to="us-gaap_PledgedStatusDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PledgedStatusDomain" xlink:label="us-gaap_PledgedStatusDomain_639069372510988001" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PledgedStatusAxis" xlink:to="us-gaap_PledgedStatusDomain_639069372510988001" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetPledgedAsCollateralMember" xlink:label="us-gaap_AssetPledgedAsCollateralMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PledgedStatusDomain" xlink:to="us-gaap_AssetPledgedAsCollateralMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="us-gaap_DebtInstrumentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentsInRealEstate" xlink:label="pfg_InvestmentsInRealEstate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="pfg_InvestmentsInRealEstate" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureDebtContingentFundingAgreementsDetails" xlink:type="extended" xlink:title="99941306 - Disclosure - Debt - Contingent Funding Agreements (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable" xlink:label="us-gaap_DebtInstrumentTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="dei_LegalEntityAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_639069372510999313" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_639069372510999313" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_Delaware2028TrustMember" xlink:label="pfg_Delaware2028TrustMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="dei_EntityDomain" xlink:to="pfg_Delaware2028TrustMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_Delaware2048TrustMember" xlink:label="pfg_Delaware2048TrustMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="dei_EntityDomain" xlink:to="pfg_Delaware2048TrustMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511004959" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511004959" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ContingentFundingAgreementMember" xlink:label="pfg_ContingentFundingAgreementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_ContingentFundingAgreementMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ContingentFundingAgreement10YearMember" xlink:label="pfg_ContingentFundingAgreement10YearMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_ContingentFundingAgreementMember" xlink:to="pfg_ContingentFundingAgreement10YearMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ContingentFundingAgreement30YearMember" xlink:label="pfg_ContingentFundingAgreement30YearMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_ContingentFundingAgreementMember" xlink:to="pfg_ContingentFundingAgreement30YearMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis" xlink:label="srt_CounterpartyNameAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="srt_CounterpartyNameAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="srt_RepurchaseAgreementCounterpartyNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_CounterpartyNameAxis" xlink:to="srt_RepurchaseAgreementCounterpartyNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="srt_RepurchaseAgreementCounterpartyNameDomain_639069372511010595" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_CounterpartyNameAxis" xlink:to="srt_RepurchaseAgreementCounterpartyNameDomain_639069372511010595" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RepurchaseAgreementCounterpartyNameDomain" xlink:to="pfg_Delaware2028TrustMember" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_RepurchaseAgreementCounterpartyNameDomain" xlink:to="pfg_Delaware2048TrustMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_Delaware2055TrustMember" xlink:label="pfg_Delaware2055TrustMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_RepurchaseAgreementCounterpartyNameDomain" xlink:to="pfg_Delaware2055TrustMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain_639069372511016314" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain_639069372511016314" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeniorNotesDue2028Member" xlink:label="pfg_SeniorNotesDue2028Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_SeniorNotesDue2028Member" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeniorNotesDue2048Member" xlink:label="pfg_SeniorNotesDue2048Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_SeniorNotesDue2048Member" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeniorNotesDue2055Member" xlink:label="pfg_SeniorNotesDue2055Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_SeniorNotesDue2055Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NotesPayable3.4PercentDue2025Member" xlink:label="pfg_NotesPayable3.4PercentDue2025Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="pfg_NotesPayable3.4PercentDue2025Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="us-gaap_LongtermDebtTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="5" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_LongtermDebtTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="us-gaap_LongtermDebtTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="us-gaap_LongtermDebtTypeDomain_639069372511021942" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain_639069372511021942" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember" xlink:label="us-gaap_SeniorNotesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="us-gaap_SeniorNotesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="us-gaap_DebtInstrumentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NumberOfContingentFundingAgreements" xlink:label="pfg_NumberOfContingentFundingAgreements" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="pfg_NumberOfContingentFundingAgreements" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TermOfContingentFundingAgreement" xlink:label="pfg_TermOfContingentFundingAgreement" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="pfg_TermOfContingentFundingAgreement" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PreCapitalizedTrustSecuritiesSold" xlink:label="pfg_PreCapitalizedTrustSecuritiesSold" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="pfg_PreCapitalizedTrustSecuritiesSold" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount" xlink:label="us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PercentageOfSemiAnnualPremiumOnOptionsUnexercisedPortion" xlink:label="pfg_PercentageOfSemiAnnualPremiumOnOptionsUnexercisedPortion" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="pfg_PercentageOfSemiAnnualPremiumOnOptionsUnexercisedPortion" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PercentageOfAnnualPremiumOnOptionsUnexercisedPortion" xlink:label="pfg_PercentageOfAnnualPremiumOnOptionsUnexercisedPortion" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="pfg_PercentageOfAnnualPremiumOnOptionsUnexercisedPortion" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="us-gaap_DebtInstrumentFaceAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentFaceAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfDebt" xlink:label="us-gaap_RepaymentsOfDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_RepaymentsOfDebt" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureIncomeTaxesEffectiveIncomeTaxRateDetails" xlink:type="extended" xlink:title="99941402 - Disclosure - Income Taxes - Effective Income Tax Rate (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeTaxAuthorityTable" xlink:label="pfg_IncomeTaxAuthorityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="us-gaap_IncomeTaxAuthorityAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_IncomeTaxAuthorityTable" xlink:to="us-gaap_IncomeTaxAuthorityAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="us-gaap_IncomeTaxAuthorityDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="us-gaap_IncomeTaxAuthorityDomain_639069372511050167" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityDomain_639069372511050167" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_IE" xlink:label="country_IE" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="country_IE" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignTaxJurisdictionOtherMember" xlink:label="us-gaap_ForeignTaxJurisdictionOtherMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="us-gaap_ForeignTaxJurisdictionOtherMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_IA" xlink:label="stpr_IA" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="stpr_IA" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_CA" xlink:label="stpr_CA" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="stpr_CA" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_IL" xlink:label="stpr_IL" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="stpr_IL" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_IncomeTaxAuthorityTable" xlink:to="srt_RangeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639069372511056453" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_639069372511056453" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeTaxAuthorityLineItems" xlink:label="pfg_IncomeTaxAuthorityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_IncomeTaxAuthorityLineItems" xlink:to="pfg_IncomeTaxAuthorityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract" xlink:label="us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_IncomeTaxAuthorityLineItems" xlink:to="us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:label="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract" xlink:to="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:label="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract" xlink:to="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalJurisdictionContributionGreaterThan50PercentTaxEffectExtensibleEnumeration" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalJurisdictionContributionGreaterThan50PercentTaxEffectExtensibleEnumeration" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalJurisdictionContributionGreaterThan50PercentTaxEffectExtensibleEnumeration" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EffectiveIncomeTaxRateReconciliationForeignTaxEffectAmountAbstract" xlink:label="pfg_EffectiveIncomeTaxRateReconciliationForeignTaxEffectAmountAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract" xlink:to="pfg_EffectiveIncomeTaxRateReconciliationForeignTaxEffectAmountAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:label="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_EffectiveIncomeTaxRateReconciliationForeignTaxEffectAmountAbstract" xlink:to="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderTaxEffectAmountAbstract" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderTaxEffectAmountAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderTaxEffectAmountAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderTaxEffectAmount" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderTaxEffectAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderTaxEffectAmountAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderTaxEffectAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsAbstract" xlink:label="us-gaap_IncomeTaxReconciliationTaxCreditsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract" xlink:to="us-gaap_IncomeTaxReconciliationTaxCreditsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsForeign" xlink:label="us-gaap_IncomeTaxReconciliationTaxCreditsForeign" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncomeTaxReconciliationTaxCreditsAbstract" xlink:to="us-gaap_IncomeTaxReconciliationTaxCreditsForeign" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsOther" xlink:label="us-gaap_IncomeTaxReconciliationTaxCreditsOther" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_IncomeTaxReconciliationTaxCreditsAbstract" xlink:to="us-gaap_IncomeTaxReconciliationTaxCreditsOther" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseAbstract" xlink:label="us-gaap_IncomeTaxReconciliationNondeductibleExpenseAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract" xlink:to="us-gaap_IncomeTaxReconciliationNondeductibleExpenseAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationDeductionsDividends" xlink:label="us-gaap_IncomeTaxReconciliationDeductionsDividends" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncomeTaxReconciliationNondeductibleExpenseAbstract" xlink:to="us-gaap_IncomeTaxReconciliationDeductionsDividends" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationEquityInEarningsLossesOfUnconsolidatedSubsidiary" xlink:label="us-gaap_IncomeTaxReconciliationEquityInEarningsLossesOfUnconsolidatedSubsidiary" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_IncomeTaxReconciliationNondeductibleExpenseAbstract" xlink:to="us-gaap_IncomeTaxReconciliationEquityInEarningsLossesOfUnconsolidatedSubsidiary" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationTaxExemptIncome" xlink:label="us-gaap_IncomeTaxReconciliationTaxExemptIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_IncomeTaxReconciliationNondeductibleExpenseAbstract" xlink:to="us-gaap_IncomeTaxReconciliationTaxExemptIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther" xlink:label="us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_IncomeTaxReconciliationNondeductibleExpenseAbstract" xlink:to="us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EffectiveIncomeTaxRateReconciliationChangeInUnrecognizedTaxBenefitsAmount" xlink:label="pfg_EffectiveIncomeTaxRateReconciliationChangeInUnrecognizedTaxBenefitsAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract" xlink:to="pfg_EffectiveIncomeTaxRateReconciliationChangeInUnrecognizedTaxBenefitsAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract" xlink:to="us-gaap_IncomeTaxExpenseBenefit" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_IncomeTaxAuthorityLineItems" xlink:to="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationDeductionsDividends" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationDeductionsDividends" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationDeductionsDividends" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderTaxEffectPercent" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderTaxEffectPercent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderTaxEffectPercent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxCredits" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationTaxCredits" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationTaxCredits" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationEquityInEarningsLossesOfUnconsolidatedSubsidiary" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationEquityInEarningsLossesOfUnconsolidatedSubsidiary" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationEquityInEarningsLossesOfUnconsolidatedSubsidiary" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxExemptIncome" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationTaxExemptIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationTaxExemptIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EffectiveIncomeTaxRateReconciliationForeignCurrencyInflationPercent" xlink:label="pfg_EffectiveIncomeTaxRateReconciliationForeignCurrencyInflationPercent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="pfg_EffectiveIncomeTaxRateReconciliationForeignCurrencyInflationPercent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EffectiveIncomeTaxRateReconciliationLowIncomeHousingTaxCreditAmortizationPercent" xlink:label="pfg_EffectiveIncomeTaxRateReconciliationLowIncomeHousingTaxCreditAmortizationPercent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="pfg_EffectiveIncomeTaxRateReconciliationLowIncomeHousingTaxCreditAmortizationPercent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsForeign" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsForeign" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsForeign" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsOther" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsOther" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsOther" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="15" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationGiltiPercent" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationGiltiPercent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="16" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationGiltiPercent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="17" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperations" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="18" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateContinuingOperations" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureIncomeTaxesDeferredIncomeTaxesAndOtherDetails" xlink:type="extended" xlink:title="99941405 - Disclosure - Income Taxes - Deferred Income Taxes and Other (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeTaxAuthorityTable" xlink:label="pfg_IncomeTaxAuthorityTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="us-gaap_IncomeTaxAuthorityAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_IncomeTaxAuthorityTable" xlink:to="us-gaap_IncomeTaxAuthorityAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="us-gaap_IncomeTaxAuthorityDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="us-gaap_IncomeTaxAuthorityDomain_639069372511126178" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityDomain_639069372511126178" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DomesticCountryMember" xlink:label="us-gaap_DomesticCountryMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="us-gaap_DomesticCountryMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US" xlink:label="country_US" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DomesticCountryMember" xlink:to="country_US" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="us-gaap_StateAndLocalJurisdictionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="country_US" xlink:to="us-gaap_StateAndLocalJurisdictionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCountryMember" xlink:label="us-gaap_ForeignCountryMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="us-gaap_ForeignCountryMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeTaxAuthorityLineItems" xlink:label="pfg_IncomeTaxAuthorityLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_IncomeTaxAuthorityLineItems" xlink:to="pfg_IncomeTaxAuthorityTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract" xlink:label="us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_IncomeTaxAuthorityLineItems" xlink:to="us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:label="us-gaap_ComponentsOfDeferredTaxAssetsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract" xlink:to="us-gaap_ComponentsOfDeferredTaxAssetsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredTaxAssetsOperatingLossCarryforwardsAndCapitalLossCarryforwards" xlink:label="pfg_DeferredTaxAssetsOperatingLossCarryforwardsAndCapitalLossCarryforwards" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:to="pfg_DeferredTaxAssetsOperatingLossCarryforwardsAndCapitalLossCarryforwards" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwards" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwards" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:to="us-gaap_DeferredTaxAssetsTaxCreditCarryforwards" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross" xlink:label="us-gaap_DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:to="us-gaap_DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:to="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsGross" xlink:label="us-gaap_DeferredTaxAssetsGross" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:to="us-gaap_DeferredTaxAssetsGross" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:to="us-gaap_DeferredTaxAssetsValuationAllowance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsNet" xlink:label="us-gaap_DeferredTaxAssetsNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:to="us-gaap_DeferredTaxAssetsNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:label="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract" xlink:to="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredTaxLiabilitiesDeferredAcquisitionCosts" xlink:label="pfg_DeferredTaxLiabilitiesDeferredAcquisitionCosts" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:to="pfg_DeferredTaxLiabilitiesDeferredAcquisitionCosts" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredTaxLiabilitiesInvestmentIncludingDerivativeAssets" xlink:label="pfg_DeferredTaxLiabilitiesInvestmentIncludingDerivativeAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:to="pfg_DeferredTaxLiabilitiesInvestmentIncludingDerivativeAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredTaxLiabilitiesFundsWithheldEmbeddedDerivatives" xlink:label="pfg_DeferredTaxLiabilitiesFundsWithheldEmbeddedDerivatives" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:to="pfg_DeferredTaxLiabilitiesFundsWithheldEmbeddedDerivatives" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredTaxLiabilitiesRealEstate" xlink:label="pfg_DeferredTaxLiabilitiesRealEstate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:to="pfg_DeferredTaxLiabilitiesRealEstate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xlink:label="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:to="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredTaxLiabilitiesPolicyholderLiabilities" xlink:label="pfg_DeferredTaxLiabilitiesPolicyholderLiabilities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:to="pfg_DeferredTaxLiabilitiesPolicyholderLiabilities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxLiabilitiesOther" xlink:label="us-gaap_DeferredTaxLiabilitiesOther" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:to="us-gaap_DeferredTaxLiabilitiesOther" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxLiabilities" xlink:label="us-gaap_DeferredIncomeTaxLiabilities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:to="us-gaap_DeferredIncomeTaxLiabilities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxLiabilities" xlink:label="us-gaap_DeferredTaxLiabilities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract" xlink:to="us-gaap_DeferredTaxLiabilities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxLiabilitiesNetAbstract" xlink:label="us-gaap_DeferredTaxLiabilitiesNetAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_IncomeTaxAuthorityLineItems" xlink:to="us-gaap_DeferredTaxLiabilitiesNetAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxAssetsNet" xlink:label="us-gaap_DeferredIncomeTaxAssetsNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DeferredTaxLiabilitiesNetAbstract" xlink:to="us-gaap_DeferredIncomeTaxAssetsNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DeferredTaxLiabilitiesNetAbstract" xlink:to="us-gaap_DeferredIncomeTaxLiabilitiesNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredIncomeTaxDisclosuresOperatingLossCarryforwardsAbstract" xlink:label="pfg_DeferredIncomeTaxDisclosuresOperatingLossCarryforwardsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_IncomeTaxAuthorityLineItems" xlink:to="pfg_DeferredIncomeTaxDisclosuresOperatingLossCarryforwardsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="us-gaap_OperatingLossCarryforwards" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_DeferredIncomeTaxDisclosuresOperatingLossCarryforwardsAbstract" xlink:to="us-gaap_OperatingLossCarryforwards" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxCreditCarryforwardAmount" xlink:label="us-gaap_TaxCreditCarryforwardAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_DeferredIncomeTaxDisclosuresOperatingLossCarryforwardsAbstract" xlink:to="us-gaap_TaxCreditCarryforwardAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CapitalLossCarryForwards" xlink:label="pfg_CapitalLossCarryForwards" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_DeferredIncomeTaxDisclosuresOperatingLossCarryforwardsAbstract" xlink:to="pfg_CapitalLossCarryForwards" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwardsValuationAllowance" xlink:label="us-gaap_OperatingLossCarryforwardsValuationAllowance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_DeferredIncomeTaxDisclosuresOperatingLossCarryforwardsAbstract" xlink:to="us-gaap_OperatingLossCarryforwardsValuationAllowance" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsPlanInformationDetails" xlink:type="extended" xlink:title="99941501 - Disclosure - Employee and Agent Benefits - Plan Information (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_RetirementPlanTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_639069372511171196" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_639069372511171196" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="us-gaap_PensionPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_PensionPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanFinalAveragePayBenefitComputationPeriodOfEmployment" xlink:label="pfg_DefinedBenefitPlanFinalAveragePayBenefitComputationPeriodOfEmployment" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="pfg_DefinedBenefitPlanFinalAveragePayBenefitComputationPeriodOfEmployment" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsBenefitObligationAndFundedStatusDetails" xlink:type="extended" xlink:title="99941502 - Disclosure - Employee and Agent Benefits - Benefit Obligation and Funded Status (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_RetirementPlanTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_639069372511182458" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_639069372511182458" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="us-gaap_PensionPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_PensionPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:label="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanBenefitObligation" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanServiceCost" xlink:label="us-gaap_DefinedBenefitPlanServiceCost" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanServiceCost" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:label="us-gaap_DefinedBenefitPlanInterestCost" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanInterestCost" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss" xlink:label="us-gaap_DefinedBenefitPlanActuarialGainLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanActuarialGainLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanSettlementsBenefitObligation" xlink:label="us-gaap_DefinedBenefitPlanSettlementsBenefitObligation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward" xlink:to="us-gaap_DefinedBenefitPlanSettlementsBenefitObligation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:label="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" xlink:label="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:label="us-gaap_DefinedBenefitPlanContributionsByEmployer" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanContributionsByEmployer" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanSettlementsPlanAssets" xlink:label="us-gaap_DefinedBenefitPlanSettlementsPlanAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward" xlink:to="us-gaap_DefinedBenefitPlanSettlementsPlanAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:label="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" xlink:label="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent" xlink:label="us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet" xlink:label="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" xlink:label="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax" xlink:label="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" xlink:to="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax" xlink:label="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" xlink:to="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax" xlink:label="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" xlink:to="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanAdditionalDisclosuresAbstract" xlink:label="pfg_DefinedBenefitPlanAdditionalDisclosuresAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="pfg_DefinedBenefitPlanAdditionalDisclosuresAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation" xlink:label="us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_DefinedBenefitPlanAdditionalDisclosuresAbstract" xlink:to="us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanNonqualifiedPensionPlanMarketValueOfAssetsHeldInTrust" xlink:label="pfg_DefinedBenefitPlanNonqualifiedPensionPlanMarketValueOfAssetsHeldInTrust" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_DefinedBenefitPlanAdditionalDisclosuresAbstract" xlink:to="pfg_DefinedBenefitPlanNonqualifiedPensionPlanMarketValueOfAssetsHeldInTrust" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsAboInExcessOfPlanAssetsDetails" xlink:type="extended" xlink:title="99941503 - Disclosure - Employee and Agent Benefits - ABO in Excess of Plan Assets (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_RetirementPlanTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_639069372511239182" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_639069372511239182" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="us-gaap_PensionPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_PensionPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" xlink:label="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation" xlink:label="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" xlink:to="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation" xlink:label="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" xlink:to="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets" xlink:label="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract" xlink:to="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsNetPeriodicBenefitCostDetails" xlink:type="extended" xlink:title="99941504 - Disclosure - Employee and Agent Benefits - Net Periodic Benefit Cost (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_RetirementPlanTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_639069372511250576" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_639069372511250576" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="us-gaap_PensionPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_PensionPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanServiceCost" xlink:label="us-gaap_DefinedBenefitPlanServiceCost" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanServiceCost" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:label="us-gaap_DefinedBenefitPlanInterestCost" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanInterestCost" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditInterestCostStatementOfIncomeOrComprehensiveIncomeExtensibleList" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditInterestCostStatementOfIncomeOrComprehensiveIncomeExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanInterestCost" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditInterestCostStatementOfIncomeOrComprehensiveIncomeExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:label="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditExpectedReturnLossStatementOfIncomeOrComprehensiveIncomeExtensibleList" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditExpectedReturnLossStatementOfIncomeOrComprehensiveIncomeExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditExpectedReturnLossStatementOfIncomeOrComprehensiveIncomeExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" xlink:label="us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditAmortizationOfPriorServiceCostCreditStatementOfIncomeOrComprehensiveIncomeExtensibleList" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditAmortizationOfPriorServiceCostCreditStatementOfIncomeOrComprehensiveIncomeExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditAmortizationOfPriorServiceCostCreditStatementOfIncomeOrComprehensiveIncomeExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses" xlink:label="us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditAmortizationOfGainLossStatementOfIncomeOrComprehensiveIncomeExtensibleList" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditAmortizationOfGainLossStatementOfIncomeOrComprehensiveIncomeExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditAmortizationOfGainLossStatementOfIncomeOrComprehensiveIncomeExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1" xlink:label="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditSettlementGainLossStatementOfIncomeOrComprehensiveIncomeExtensibleList" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditSettlementGainLossStatementOfIncomeOrComprehensiveIncomeExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditSettlementGainLossStatementOfIncomeOrComprehensiveIncomeExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanActuarialGainLossAmortizationDisclosuresAbstract" xlink:label="pfg_DefinedBenefitPlanActuarialGainLossAmortizationDisclosuresAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="pfg_DefinedBenefitPlanActuarialGainLossAmortizationDisclosuresAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanQualifiedPensionPlanActuarialGainsAndLossesAmortizationAllowanceCorridorNotUsed" xlink:label="pfg_DefinedBenefitPlanQualifiedPensionPlanActuarialGainsAndLossesAmortizationAllowanceCorridorNotUsed" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_DefinedBenefitPlanActuarialGainLossAmortizationDisclosuresAbstract" xlink:to="pfg_DefinedBenefitPlanQualifiedPensionPlanActuarialGainsAndLossesAmortizationAllowanceCorridorNotUsed" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:label="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmountRecognizedInNetPeriodicBenefitCostAndOtherComprehensiveIncomeLossBeforeTax" xlink:label="us-gaap_AmountRecognizedInNetPeriodicBenefitCostAndOtherComprehensiveIncomeLossBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_AmountRecognizedInNetPeriodicBenefitCostAndOtherComprehensiveIncomeLossBeforeTax" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsWeightedAverageAssumptionsDetails" xlink:type="extended" xlink:title="99941505 - Disclosure - Employee and Agent Benefits - Weighted Average Assumptions (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_RetirementPlanTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_639069372511291373" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_639069372511291373" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="us-gaap_PensionPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_PensionPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_HomeOfficeAndAgentPre65MedicalLifePlanMember" xlink:label="pfg_HomeOfficeAndAgentPre65MedicalLifePlanMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:to="pfg_HomeOfficeAndAgentPre65MedicalLifePlanMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_Post65MedicalPlansMember" xlink:label="pfg_Post65MedicalPlansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:to="pfg_Post65MedicalPlansMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="srt_RangeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639069372511297030" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_639069372511297030" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_RetirementPlanParticipantsEntryByDateAxis" xlink:label="pfg_RetirementPlanParticipantsEntryByDateAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="pfg_RetirementPlanParticipantsEntryByDateAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_RetirementPlanParticipantsEntryByDateDomain" xlink:label="pfg_RetirementPlanParticipantsEntryByDateDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="pfg_RetirementPlanParticipantsEntryByDateAxis" xlink:to="pfg_RetirementPlanParticipantsEntryByDateDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_RetirementPlanParticipantsEntryByDateDomain" xlink:label="pfg_RetirementPlanParticipantsEntryByDateDomain_639069372511297030" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="pfg_RetirementPlanParticipantsEntryByDateAxis" xlink:to="pfg_RetirementPlanParticipantsEntryByDateDomain_639069372511297030" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ParticipantsEnteredBeforeJuly12019Member" xlink:label="pfg_ParticipantsEnteredBeforeJuly12019Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_RetirementPlanParticipantsEntryByDateDomain" xlink:to="pfg_ParticipantsEnteredBeforeJuly12019Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ParticipantsEnteredOnAndAfterJuly12019Member" xlink:label="pfg_ParticipantsEnteredOnAndAfterJuly12019Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_RetirementPlanParticipantsEntryByDateDomain" xlink:to="pfg_ParticipantsEnteredOnAndAfterJuly12019Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract" xlink:label="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:label="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostWeightedAverageInterestCreditingRate" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostWeightedAverageInterestCreditingRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostWeightedAverageInterestCreditingRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostFixedInterestCreditingRate" xlink:label="pfg_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostFixedInterestCreditingRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:to="pfg_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostFixedInterestCreditingRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostInterestCreditingRateBasedOnIndexationOfTreasuryRate" xlink:label="pfg_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostInterestCreditingRateBasedOnIndexationOfTreasuryRate" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract" xlink:to="pfg_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostInterestCreditingRateBasedOnIndexationOfTreasuryRate" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumedHealthCareCostTrendRatesAbstract" xlink:label="us-gaap_DefinedBenefitPlanAssumedHealthCareCostTrendRatesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanAssumedHealthCareCostTrendRatesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearUnderAge65" xlink:label="pfg_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearUnderAge65" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanAssumedHealthCareCostTrendRatesAbstract" xlink:to="pfg_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearUnderAge65" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearAge65AndOver" xlink:label="pfg_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearAge65AndOver" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanAssumedHealthCareCostTrendRatesAbstract" xlink:to="pfg_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearAge65AndOver" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1" xlink:label="us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanAssumedHealthCareCostTrendRatesAbstract" xlink:to="us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanYearThatRateReachesUltimateTrendRateUnderAge65" xlink:label="pfg_DefinedBenefitPlanYearThatRateReachesUltimateTrendRateUnderAge65" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlanAssumedHealthCareCostTrendRatesAbstract" xlink:to="pfg_DefinedBenefitPlanYearThatRateReachesUltimateTrendRateUnderAge65" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanYearThatRateReachesUltimateTrendRateAge65AndOver" xlink:label="pfg_DefinedBenefitPlanYearThatRateReachesUltimateTrendRateAge65AndOver" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DefinedBenefitPlanAssumedHealthCareCostTrendRatesAbstract" xlink:to="pfg_DefinedBenefitPlanYearThatRateReachesUltimateTrendRateAge65AndOver" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsFairValueOfPlanAssetsDetails" xlink:type="extended" xlink:title="99941506 - Disclosure - Employee and Agent Benefits - Fair Value of Plan Assets (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_RetirementPlanTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_639069372511331010" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_639069372511331010" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="us-gaap_PensionPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_PensionPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_639069372511336680" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_639069372511336680" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember" xlink:label="us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="us-gaap_FairValueInputsLevel1Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel1Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="us-gaap_FairValueInputsLevel2Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeAxis" xlink:label="us-gaap_InvestmentTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_InvestmentTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember_639069372511342317" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember_639069372511342317" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PooledSeparateAccountInvestmentsMember" xlink:label="pfg_PooledSeparateAccountInvestmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="pfg_PooledSeparateAccountInvestmentsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SingleClientSeparateAccountInvestmentsMember" xlink:label="pfg_SingleClientSeparateAccountInvestmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="pfg_SingleClientSeparateAccountInvestmentsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:label="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="us-gaap_PlanAssetCategoriesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:to="us-gaap_PlanAssetCategoriesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="us-gaap_PlanAssetCategoriesDomain_639069372511348020" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:to="us-gaap_PlanAssetCategoriesDomain_639069372511348020" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanCashAndCashEquivalentsMember" xlink:label="us-gaap_DefinedBenefitPlanCashAndCashEquivalentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_DefinedBenefitPlanCashAndCashEquivalentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedIncomeSecuritiesMember" xlink:label="us-gaap_FixedIncomeSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_FixedIncomeSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesUsMember" xlink:label="us-gaap_DefinedBenefitPlanEquitySecuritiesUsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_DefinedBenefitPlanEquitySecuritiesUsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesUsLargeCapMember" xlink:label="us-gaap_DefinedBenefitPlanEquitySecuritiesUsLargeCapMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanEquitySecuritiesUsMember" xlink:to="us-gaap_DefinedBenefitPlanEquitySecuritiesUsLargeCapMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanEquitySecuritiesUsSmallMidCapMember" xlink:label="pfg_DefinedBenefitPlanEquitySecuritiesUsSmallMidCapMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanEquitySecuritiesUsMember" xlink:to="pfg_DefinedBenefitPlanEquitySecuritiesUsSmallMidCapMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_BalancedAssetAllocationPortfoliosMember" xlink:label="pfg_BalancedAssetAllocationPortfoliosMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="pfg_BalancedAssetAllocationPortfoliosMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesNonUsMember" xlink:label="us-gaap_DefinedBenefitPlanEquitySecuritiesNonUsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_DefinedBenefitPlanEquitySecuritiesNonUsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanRealEstateMember" xlink:label="us-gaap_DefinedBenefitPlanRealEstateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_DefinedBenefitPlanRealEstateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDebtSecurityMember" xlink:label="us-gaap_DefinedBenefitPlanDebtSecurityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_DefinedBenefitPlanDebtSecurityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasuryAndGovernmentMember" xlink:label="us-gaap_USTreasuryAndGovernmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanDebtSecurityMember" xlink:to="us-gaap_USTreasuryAndGovernmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember" xlink:label="us-gaap_USStatesAndPoliticalSubdivisionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanDebtSecurityMember" xlink:to="us-gaap_USStatesAndPoliticalSubdivisionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="us-gaap_CorporateDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanDebtSecurityMember" xlink:to="us-gaap_CorporateDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PrivateEquityFundsMember" xlink:label="us-gaap_PrivateEquityFundsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_PrivateEquityFundsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MutualFundMember" xlink:label="us-gaap_MutualFundMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_MutualFundMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SingleClientSeparateAccountsInvestedInPooledSeparateAccountMember" xlink:label="pfg_SingleClientSeparateAccountsInvestedInPooledSeparateAccountMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="pfg_SingleClientSeparateAccountsInvestedInPooledSeparateAccountMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherPlanAssetsMember" xlink:label="pfg_OtherPlanAssetsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="pfg_OtherPlanAssetsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedBenefitPlanFairValueOfPlanAssetsAbstract" xlink:label="pfg_DefinedBenefitPlanFairValueOfPlanAssetsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="pfg_DefinedBenefitPlanFairValueOfPlanAssetsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_DefinedBenefitPlanFairValueOfPlanAssetsAbstract" xlink:to="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanTaxStatusExtensibleList" xlink:label="us-gaap_DefinedBenefitPlanTaxStatusExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanTaxStatusExtensibleList" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsTargetPlanAssetAllocationDetails" xlink:type="extended" xlink:title="99941507 - Disclosure - Employee and Agent Benefits - Target Plan Asset Allocation (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_RetirementPlanTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_639069372511387618" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_639069372511387618" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="us-gaap_PensionPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_PensionPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:label="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="us-gaap_PlanAssetCategoriesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:to="us-gaap_PlanAssetCategoriesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="us-gaap_PlanAssetCategoriesDomain_639069372511393325" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:to="us-gaap_PlanAssetCategoriesDomain_639069372511393325" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesUsMember" xlink:label="us-gaap_DefinedBenefitPlanEquitySecuritiesUsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_DefinedBenefitPlanEquitySecuritiesUsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesNonUsMember" xlink:label="us-gaap_DefinedBenefitPlanEquitySecuritiesNonUsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_DefinedBenefitPlanEquitySecuritiesNonUsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedIncomeSecuritiesMember" xlink:label="us-gaap_FixedIncomeSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_FixedIncomeSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesMember" xlink:label="us-gaap_DefinedBenefitPlanEquitySecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="us-gaap_DefinedBenefitPlanEquitySecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PrivateInvestmentsMember" xlink:label="pfg_PrivateInvestmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_PlanAssetCategoriesDomain" xlink:to="pfg_PrivateInvestmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract" xlink:label="us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract" xlink:to="us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanTaxStatusExtensibleList" xlink:label="us-gaap_DefinedBenefitPlanTaxStatusExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage" xlink:to="us-gaap_DefinedBenefitPlanTaxStatusExtensibleList" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsContributionsAndEstimatedFutureBenefitPaymentsDetails" xlink:type="extended" xlink:title="99941508 - Disclosure - Employee and Agent Benefits - Contributions and Estimated Future Benefit Payments (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_RetirementPlanTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_639069372511410320" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_639069372511410320" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="us-gaap_PensionPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_PensionPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="srt_RangeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639069372511410320" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_639069372511410320" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsAbstract" xlink:label="us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:label="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsSupplementalInformationQualifiedAndNonqualifiedPlansDetails" xlink:type="extended" xlink:title="99941509 - Disclosure - Employee and Agent Benefits - Supplemental Information, Qualified and Nonqualified Plans (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_RetirementPlanTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_639069372511432929" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_639069372511432929" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="us-gaap_PensionPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_PensionPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTaxStatusAxis" xlink:label="us-gaap_RetirementPlanTaxStatusAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="us-gaap_RetirementPlanTaxStatusAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTaxStatusDomain" xlink:label="us-gaap_RetirementPlanTaxStatusDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTaxStatusAxis" xlink:to="us-gaap_RetirementPlanTaxStatusDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTaxStatusDomain" xlink:label="us-gaap_RetirementPlanTaxStatusDomain_639069372511432929" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTaxStatusAxis" xlink:to="us-gaap_RetirementPlanTaxStatusDomain_639069372511432929" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_QualifiedPlanMember" xlink:label="us-gaap_QualifiedPlanMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTaxStatusDomain" xlink:to="us-gaap_QualifiedPlanMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonqualifiedPlanMember" xlink:label="us-gaap_NonqualifiedPlanMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_RetirementPlanTaxStatusDomain" xlink:to="us-gaap_NonqualifiedPlanMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="us-gaap_DefinedBenefitPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:label="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" xlink:label="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent" xlink:label="us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet" xlink:label="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract" xlink:to="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" xlink:label="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax" xlink:label="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" xlink:to="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax" xlink:label="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" xlink:to="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax" xlink:label="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract" xlink:to="us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanServiceCost" xlink:label="us-gaap_DefinedBenefitPlanServiceCost" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanServiceCost" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:label="us-gaap_DefinedBenefitPlanInterestCost" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanInterestCost" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:label="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" xlink:label="us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses" xlink:label="us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1" xlink:label="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:label="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmountRecognizedInNetPeriodicBenefitCostAndOtherComprehensiveIncomeLossBeforeTax" xlink:label="us-gaap_AmountRecognizedInNetPeriodicBenefitCostAndOtherComprehensiveIncomeLossBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_AmountRecognizedInNetPeriodicBenefitCostAndOtherComprehensiveIncomeLossBeforeTax" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEmployeeAndAgentBenefitsDefinedContributionAndDeferredCompensationPlansDetails" xlink:type="extended" xlink:title="99941510 - Disclosure - Employee and Agent Benefits - Defined Contribution and Deferred Compensation Plans (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanTable" xlink:label="us-gaap_DefinedContributionPlanTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DefinedContributionPlanTable" xlink:to="us-gaap_RetirementPlanTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_639069372511495018" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_639069372511495018" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="us-gaap_PensionPlansDefinedBenefitMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_PensionPlansDefinedBenefitMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedContributionPlanGrandfatheredChoiceParticipantMember" xlink:label="pfg_DefinedContributionPlanGrandfatheredChoiceParticipantMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PensionPlansDefinedBenefitMember" xlink:to="pfg_DefinedContributionPlanGrandfatheredChoiceParticipantMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedContributionPlanGeneralParticipantMember" xlink:label="pfg_DefinedContributionPlanGeneralParticipantMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PensionPlansDefinedBenefitMember" xlink:to="pfg_DefinedContributionPlanGeneralParticipantMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTaxStatusAxis" xlink:label="us-gaap_RetirementPlanTaxStatusAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DefinedContributionPlanTable" xlink:to="us-gaap_RetirementPlanTaxStatusAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTaxStatusDomain" xlink:label="us-gaap_RetirementPlanTaxStatusDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_RetirementPlanTaxStatusAxis" xlink:to="us-gaap_RetirementPlanTaxStatusDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTaxStatusDomain" xlink:label="us-gaap_RetirementPlanTaxStatusDomain_639069372511500764" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_RetirementPlanTaxStatusAxis" xlink:to="us-gaap_RetirementPlanTaxStatusDomain_639069372511500764" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_QualifiedPlanMember" xlink:label="us-gaap_QualifiedPlanMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RetirementPlanTaxStatusDomain" xlink:to="us-gaap_QualifiedPlanMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonqualifiedPlanMember" xlink:label="us-gaap_NonqualifiedPlanMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_RetirementPlanTaxStatusDomain" xlink:to="us-gaap_NonqualifiedPlanMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanDisclosureLineItems" xlink:label="us-gaap_DefinedContributionPlanDisclosureLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DefinedContributionPlanDisclosureLineItems" xlink:to="us-gaap_DefinedContributionPlanTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount" xlink:label="us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DefinedContributionPlanDisclosureLineItems" xlink:to="us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch" xlink:label="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DefinedContributionPlanDisclosureLineItems" xlink:to="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" xlink:label="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DefinedContributionPlanDisclosureLineItems" xlink:to="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DefinedContributionPlanContributionsByEmployer" xlink:label="pfg_DefinedContributionPlanContributionsByEmployer" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DefinedContributionPlanDisclosureLineItems" xlink:to="pfg_DefinedContributionPlanContributionsByEmployer" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOwnershipPlanESOPNumberOfAllocatedShares" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPNumberOfAllocatedShares" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DefinedContributionPlanDisclosureLineItems" xlink:to="us-gaap_EmployeeStockOwnershipPlanESOPNumberOfAllocatedShares" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EmployeeStockOwnershipPlanESOPEarnedAndUnearnedDeferredSharesFairValue" xlink:label="pfg_EmployeeStockOwnershipPlanESOPEarnedAndUnearnedDeferredSharesFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DefinedContributionPlanDisclosureLineItems" xlink:to="pfg_EmployeeStockOwnershipPlanESOPEarnedAndUnearnedDeferredSharesFairValue" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureContingenciesGuaranteesIndemnificationsAndLeasesGuaranteesAndIndemnificationsDetails" xlink:type="extended" xlink:title="99941601 - Disclosure - Contingencies, Guarantees, Indemnifications and Leases - Guarantees and Indemnifications (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesTable" xlink:label="us-gaap_LossContingenciesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsByNatureAxis" xlink:label="us-gaap_GuaranteeObligationsByNatureAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_LossContingenciesTable" xlink:to="us-gaap_GuaranteeObligationsByNatureAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsNatureDomain" xlink:label="us-gaap_GuaranteeObligationsNatureDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_GuaranteeObligationsByNatureAxis" xlink:to="us-gaap_GuaranteeObligationsNatureDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsNatureDomain" xlink:label="us-gaap_GuaranteeObligationsNatureDomain_639069372511517801" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_GuaranteeObligationsByNatureAxis" xlink:to="us-gaap_GuaranteeObligationsNatureDomain_639069372511517801" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GuaranteesToThirdPartiesPrimarilyRelatedToFormerSubsidiariesAndJointVenturesMember" xlink:label="pfg_GuaranteesToThirdPartiesPrimarilyRelatedToFormerSubsidiariesAndJointVenturesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_GuaranteeObligationsNatureDomain" xlink:to="pfg_GuaranteesToThirdPartiesPrimarilyRelatedToFormerSubsidiariesAndJointVenturesMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GuaranteesToUnconsolidatedTrustsUnderContingentFundingAgreementsMember" xlink:label="pfg_GuaranteesToUnconsolidatedTrustsUnderContingentFundingAgreementsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_GuaranteeObligationsNatureDomain" xlink:to="pfg_GuaranteesToUnconsolidatedTrustsUnderContingentFundingAgreementsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesLineItems" xlink:label="us-gaap_LossContingenciesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_LossContingenciesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteesAbstract" xlink:label="us-gaap_GuaranteesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_GuaranteesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsMaximumExposure" xlink:label="us-gaap_GuaranteeObligationsMaximumExposure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_GuaranteesAbstract" xlink:to="us-gaap_GuaranteeObligationsMaximumExposure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GuarantyFundsAbstract" xlink:label="pfg_GuarantyFundsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="pfg_GuarantyFundsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability" xlink:label="us-gaap_LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_GuarantyFundsAbstract" xlink:to="us-gaap_LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyAccrualInsuranceRelatedAssessmentPremiumTaxOffset" xlink:label="us-gaap_LossContingencyAccrualInsuranceRelatedAssessmentPremiumTaxOffset" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_GuarantyFundsAbstract" xlink:to="us-gaap_LossContingencyAccrualInsuranceRelatedAssessmentPremiumTaxOffset" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureStockholdersEquityCommonStockDividendsAndReconciliationOfOutstandingCommonSharesDetails" xlink:type="extended" xlink:title="99941701 - Disclosure - Stockholders' Equity - Common Stock Dividends and Reconciliation of Outstanding Common Shares (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="us-gaap_ScheduleOfStockByClassTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_StatementEquityComponentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_639069372511534766" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_639069372511534766" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockLineItems" xlink:label="us-gaap_ClassOfStockLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_ScheduleOfStockByClassTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsCommonStockAbstract" xlink:label="us-gaap_DividendsCommonStockAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_DividendsCommonStockAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockDividendsPerShareDeclared" xlink:label="us-gaap_CommonStockDividendsPerShareDeclared" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DividendsCommonStockAbstract" xlink:to="us-gaap_CommonStockDividendsPerShareDeclared" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncreaseDecreaseInSharesOutstandingRollforward" xlink:label="pfg_IncreaseDecreaseInSharesOutstandingRollforward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="pfg_IncreaseDecreaseInSharesOutstandingRollforward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharesOutstanding" xlink:label="us-gaap_SharesOutstanding" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_IncreaseDecreaseInSharesOutstandingRollforward" xlink:to="us-gaap_SharesOutstanding" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_IncreaseDecreaseInSharesOutstandingRollforward" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="us-gaap_TreasuryStockSharesAcquired" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_IncreaseDecreaseInSharesOutstandingRollforward" xlink:to="us-gaap_TreasuryStockSharesAcquired" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRepurchaseOfEquityAbstract" xlink:label="us-gaap_PaymentsForRepurchaseOfEquityAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_PaymentsForRepurchaseOfEquityAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TreasuryStockAcquiredRepurchaseAuthorizationAmount" xlink:label="pfg_TreasuryStockAcquiredRepurchaseAuthorizationAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PaymentsForRepurchaseOfEquityAbstract" xlink:to="pfg_TreasuryStockAcquiredRepurchaseAuthorizationAmount" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureStockholdersEquityOtherComprehensiveIncomeLossDetails" xlink:type="extended" xlink:title="99941702 - Disclosure - Stockholders' Equity - Other Comprehensive Income (Loss) (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:to="us-gaap_StatementEquityComponentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_639069372511546031" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_639069372511546031" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedNetInvestmentGainLossIncludingPortionAttributableToNoncontrollingInterestMember" xlink:label="us-gaap_AccumulatedNetInvestmentGainLossIncludingPortionAttributableToNoncontrollingInterestMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedNetInvestmentGainLossIncludingPortionAttributableToNoncontrollingInterestMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember" xlink:label="us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociLiabilityForFuturePolicyBenefitIncludingNoncontrollingInterestMember" xlink:label="us-gaap_AociLiabilityForFuturePolicyBenefitIncludingNoncontrollingInterestMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AociLiabilityForFuturePolicyBenefitIncludingNoncontrollingInterestMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociMarketRiskBenefitInstrumentSpecificCreditRiskIncludingNoncontrollingInterestMember" xlink:label="us-gaap_AociMarketRiskBenefitInstrumentSpecificCreditRiskIncludingNoncontrollingInterestMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AociMarketRiskBenefitInstrumentSpecificCreditRiskIncludingNoncontrollingInterestMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember" xlink:label="us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember" xlink:label="us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="us-gaap_IncomeStatementLocationAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:to="us-gaap_IncomeStatementLocationAxis" priority="2" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain_639069372511557343" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain_639069372511557343" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetRealizedCapitalGainsLossesMember" xlink:label="pfg_NetRealizedCapitalGainsLossesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="pfg_NetRealizedCapitalGainsLossesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OperatingExpensesMember" xlink:label="pfg_OperatingExpensesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="pfg_OperatingExpensesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:label="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax" xlink:label="us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AdjustmentsForAssumedChangesInAmortizationPatternsBeforeTax" xlink:label="pfg_AdjustmentsForAssumedChangesInAmortizationPatternsBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="pfg_AdjustmentsForAssumedChangesInAmortizationPatternsBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AdjustmentsForAssumedChangesInLiabilityForPolicyholderBenefitsAndClaimsBeforeTax" xlink:label="pfg_AdjustmentsForAssumedChangesInLiabilityForPolicyholderBenefitsAndClaimsBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="pfg_AdjustmentsForAssumedChangesInLiabilityForPolicyholderBenefitsAndClaimsBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossBeforeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossBeforeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAociCurrentPeriodTax" xlink:label="us-gaap_ReclassificationFromAociCurrentPeriodTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_ReclassificationFromAociCurrentPeriodTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AdjustmentsForAssumedChangesInAmortizationPatternsTax" xlink:label="pfg_AdjustmentsForAssumedChangesInAmortizationPatternsTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="pfg_AdjustmentsForAssumedChangesInAmortizationPatternsTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AdjustmentsForAssumedChangesInLiabilityForPolicyholderBenefitsAndClaimsTax" xlink:label="pfg_AdjustmentsForAssumedChangesInLiabilityForPolicyholderBenefitsAndClaimsTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="pfg_AdjustmentsForAssumedChangesInLiabilityForPolicyholderBenefitsAndClaimsTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" xlink:label="us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AdjustmentsForAssumedChangesInAmortizationPatternsNetOfTax" xlink:label="pfg_AdjustmentsForAssumedChangesInAmortizationPatternsNetOfTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="pfg_AdjustmentsForAssumedChangesInAmortizationPatternsNetOfTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AdjustmentsForAssumedChangesInLiabilityForPolicyholderBenefitsAndClaimsNetOfTax" xlink:label="pfg_AdjustmentsForAssumedChangesInLiabilityForPolicyholderBenefitsAndClaimsNetOfTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="pfg_AdjustmentsForAssumedChangesInLiabilityForPolicyholderBenefitsAndClaimsNetOfTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="15" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetOfTax" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureStockholdersEquityAociAndNoncontrollingInterestDetails" xlink:type="extended" xlink:title="99941703 - Disclosure - Stockholders' Equity - AOCI and Noncontrolling Interest (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:to="us-gaap_StatementEquityComponentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_639069372511591295" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_639069372511591295" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember" xlink:label="us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:to="us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember" xlink:label="us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:to="us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociLiabilityForFuturePolicyBenefitParentMember" xlink:label="us-gaap_AociLiabilityForFuturePolicyBenefitParentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:to="us-gaap_AociLiabilityForFuturePolicyBenefitParentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociMarketRiskBenefitInstrumentSpecificCreditRiskParentMember" xlink:label="us-gaap_AociMarketRiskBenefitInstrumentSpecificCreditRiskParentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:to="us-gaap_AociMarketRiskBenefitInstrumentSpecificCreditRiskParentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedTranslationAdjustmentMember" xlink:label="us-gaap_AccumulatedTranslationAdjustmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:to="us-gaap_AccumulatedTranslationAdjustmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember" xlink:label="us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:to="us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward" xlink:label="us-gaap_AOCIAttributableToParentNetOfTaxRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_AOCIAttributableToParentNetOfTaxRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_AOCIAttributableToParentNetOfTaxRollForward" xlink:to="us-gaap_StockholdersEquity" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent" xlink:label="us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_AOCIAttributableToParentNetOfTaxRollForward" xlink:to="us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent" xlink:label="us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_AOCIAttributableToParentNetOfTaxRollForward" xlink:to="us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_AOCIAttributableToParentNetOfTaxRollForward" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AociDebtSecuritiesAvailableForSaleWithAllowanceForCreditLossCumulativeGainLossPreTax" xlink:label="pfg_AociDebtSecuritiesAvailableForSaleWithAllowanceForCreditLossCumulativeGainLossPreTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_AOCIAttributableToParentNetOfTaxRollForward" xlink:to="pfg_AociDebtSecuritiesAvailableForSaleWithAllowanceForCreditLossCumulativeGainLossPreTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" xlink:label="pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" xlink:label="us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" xlink:to="us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAttributableToRedeemableNoncontrollingInterest" xlink:label="us-gaap_NetIncomeLossAttributableToRedeemableNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" xlink:to="us-gaap_NetIncomeLossAttributableToRedeemableNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_RedeemableNoncontrollingInterestDecreaseFromDeconsolidation" xlink:label="pfg_RedeemableNoncontrollingInterestDecreaseFromDeconsolidation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" xlink:to="pfg_RedeemableNoncontrollingInterestDecreaseFromDeconsolidation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ContributionsToRedeemableNoncontrollingInterest" xlink:label="pfg_ContributionsToRedeemableNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" xlink:to="pfg_ContributionsToRedeemableNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DistributionsToRedeemableNoncontrollingInterest" xlink:label="pfg_DistributionsToRedeemableNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" xlink:to="pfg_DistributionsToRedeemableNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PurchaseOfSubsidiarySharesFromRedeemableNoncontrollingInterest" xlink:label="pfg_PurchaseOfSubsidiarySharesFromRedeemableNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" xlink:to="pfg_PurchaseOfSubsidiarySharesFromRedeemableNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MinorityInterestChangeInRedemptionValue" xlink:label="us-gaap_MinorityInterestChangeInRedemptionValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" xlink:to="us-gaap_MinorityInterestChangeInRedemptionValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_RedeemableNoncontrollingInterestChangeInShareBasedCompensation" xlink:label="pfg_RedeemableNoncontrollingInterestChangeInShareBasedCompensation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" xlink:to="pfg_RedeemableNoncontrollingInterestChangeInShareBasedCompensation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherComprehensiveIncomeLossAttributableToRedeemableNoncontrollingInterest" xlink:label="pfg_OtherComprehensiveIncomeLossAttributableToRedeemableNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="pfg_IncreaseDecreaseInRedeemableNoncontrollingInterestRollForward" xlink:to="pfg_OtherComprehensiveIncomeLossAttributableToRedeemableNoncontrollingInterest" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureStockholdersEquityDividendLimitationsDetails" xlink:type="extended" xlink:title="99941704 - Disclosure - Stockholders' Equity - Dividend Limitations (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatutoryAccountingPracticesTable" xlink:label="us-gaap_StatutoryAccountingPracticesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_StatutoryAccountingPracticesTable" xlink:to="dei_LegalEntityAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_639069372511620794" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_639069372511620794" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsidiariesPrincipalLifeInsuranceCompanyMember" xlink:label="pfg_SubsidiariesPrincipalLifeInsuranceCompanyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="dei_EntityDomain" xlink:to="pfg_SubsidiariesPrincipalLifeInsuranceCompanyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatutoryAccountingPracticesLineItems" xlink:label="us-gaap_StatutoryAccountingPracticesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_StatutoryAccountingPracticesLineItems" xlink:to="us-gaap_StatutoryAccountingPracticesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DividendRestrictionPercentageOfPolicyholdersSurplus" xlink:label="pfg_DividendRestrictionPercentageOfPolicyholdersSurplus" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_StatutoryAccountingPracticesLineItems" xlink:to="pfg_DividendRestrictionPercentageOfPolicyholdersSurplus" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPaymentsWithoutRegulatoryApproval" xlink:label="us-gaap_StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPaymentsWithoutRegulatoryApproval" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_StatutoryAccountingPracticesLineItems" xlink:to="us-gaap_StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPaymentsWithoutRegulatoryApproval" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails" xlink:type="extended" xlink:title="99941801 - Disclosure - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="us-gaap_FairValueByMeasurementFrequencyAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="us-gaap_FairValueByMeasurementFrequencyAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="us-gaap_FairValueMeasurementFrequencyDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain_639069372511632565" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="us-gaap_FairValueMeasurementFrequencyDomain_639069372511632565" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="us-gaap_FairValueMeasurementsRecurringMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueMeasurementFrequencyDomain" xlink:to="us-gaap_FairValueMeasurementsRecurringMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511638126" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511638126" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasuryAndGovernmentMember" xlink:label="us-gaap_USTreasuryAndGovernmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_USTreasuryAndGovernmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignGovernmentDebtSecuritiesMember" xlink:label="us-gaap_ForeignGovernmentDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_ForeignGovernmentDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember" xlink:label="us-gaap_USStatesAndPoliticalSubdivisionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_USStatesAndPoliticalSubdivisionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="us-gaap_CorporateDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CorporateDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember" xlink:label="us-gaap_ResidentialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_ResidentialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember" xlink:label="us-gaap_CommercialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CommercialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralizedDebtObligationsMember" xlink:label="us-gaap_CollateralizedDebtObligationsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_CollateralizedDebtObligationsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherDebtSecuritiesMember" xlink:label="us-gaap_OtherDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_OtherDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_639069372511649367" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_639069372511649367" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember" xlink:label="us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="us-gaap_FairValueInputsLevel1Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel1Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="us-gaap_FairValueInputsLevel2Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="us-gaap_FairValueInputsLevel3Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel3Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradingSecuritiesDebt" xlink:label="us-gaap_TradingSecuritiesDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_TradingSecuritiesDebt" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent" xlink:label="us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LoansReceivableFairValueDisclosure" xlink:label="us-gaap_LoansReceivableFairValueDisclosure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_LoansReceivableFairValueDisclosure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement" xlink:label="us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsMeasuredOnRecurringBasisOtherInvestments" xlink:label="pfg_FairValueAssetsMeasuredOnRecurringBasisOtherInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="pfg_FairValueAssetsMeasuredOnRecurringBasisOtherInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsMeasuredOnRecurringBasisCashEquivalents" xlink:label="pfg_FairValueAssetsMeasuredOnRecurringBasisCashEquivalents" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="pfg_FairValueAssetsMeasuredOnRecurringBasisCashEquivalents" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsMeasuredOnRecurringBasisMarketRiskBenefitAsset" xlink:label="pfg_FairValueAssetsMeasuredOnRecurringBasisMarketRiskBenefitAsset" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="pfg_FairValueAssetsMeasuredOnRecurringBasisMarketRiskBenefitAsset" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsMeasuredOnRecurringBasisTotalAssetsExcludingSeparateAccountAssets" xlink:label="pfg_FairValueAssetsMeasuredOnRecurringBasisTotalAssetsExcludingSeparateAccountAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="pfg_FairValueAssetsMeasuredOnRecurringBasisTotalAssetsExcludingSeparateAccountAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountAssets" xlink:label="us-gaap_SeparateAccountAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_SeparateAccountAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="us-gaap_AssetsFairValueDisclosure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_AssetsFairValueDisclosure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeFairValueOfDerivativeLiabilityInvestmentAndUniversalLifeContracts" xlink:label="pfg_DerivativeFairValueOfDerivativeLiabilityInvestmentAndUniversalLifeContracts" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="pfg_DerivativeFairValueOfDerivativeLiabilityInvestmentAndUniversalLifeContracts" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsMeasuredOnRecurringBasisMarketRiskBenefitLiability" xlink:label="pfg_FairValueAssetsMeasuredOnRecurringBasisMarketRiskBenefitLiability" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="pfg_FairValueAssetsMeasuredOnRecurringBasisMarketRiskBenefitLiability" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsWithheldEmbeddedDerivative" xlink:label="pfg_FundsWithheldEmbeddedDerivative" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="15" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="pfg_FundsWithheldEmbeddedDerivative" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtFairValue" xlink:label="us-gaap_LongTermDebtFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="16" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_LongTermDebtFairValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangementExcludingEmbeddedDerivatives" xlink:label="pfg_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangementExcludingEmbeddedDerivatives" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="17" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="pfg_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangementExcludingEmbeddedDerivatives" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_LiabilitiesOtherFairValueDisclosure" xlink:label="pfg_LiabilitiesOtherFairValueDisclosure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="18" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="pfg_LiabilitiesOtherFairValueDisclosure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="us-gaap_LiabilitiesFairValueDisclosure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="19" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_LiabilitiesFairValueDisclosure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisNetAssetsLiabilities" xlink:label="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisNetAssetsLiabilities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="20" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisNetAssetsLiabilities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareUnfundedCommittments" xlink:label="us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareUnfundedCommittments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="21" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareUnfundedCommittments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FixedMaturitySecuritiesValuedUsingInternalPricingModelsAbstract" xlink:label="pfg_FixedMaturitySecuritiesValuedUsingInternalPricingModelsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="22" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="pfg_FixedMaturitySecuritiesValuedUsingInternalPricingModelsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FixedMaturitySecuritiesLevel3ValuedUsingInternalPricingModels" xlink:label="pfg_FixedMaturitySecuritiesLevel3ValuedUsingInternalPricingModels" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_FixedMaturitySecuritiesValuedUsingInternalPricingModelsAbstract" xlink:to="pfg_FixedMaturitySecuritiesLevel3ValuedUsingInternalPricingModels" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFairValueMeasurementsChangesInLevel3FairValueMeasurementsDetails" xlink:type="extended" xlink:title="99941802 - Disclosure - Fair Value Measurements - Changes in Level 3 Fair Value Measurements (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:label="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="us-gaap_FairValueByMeasurementFrequencyAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:to="us-gaap_FairValueByMeasurementFrequencyAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="us-gaap_FairValueMeasurementFrequencyDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain_639069372511699792" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="us-gaap_FairValueMeasurementFrequencyDomain_639069372511699792" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="us-gaap_FairValueMeasurementsRecurringMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueMeasurementFrequencyDomain" xlink:to="us-gaap_FairValueMeasurementsRecurringMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="us-gaap_FairValueByAssetClassAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:to="us-gaap_FairValueByAssetClassAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByAssetClassAxis" xlink:to="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_639069372511699792" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByAssetClassAxis" xlink:to="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_639069372511699792" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesMember" xlink:label="us-gaap_DebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="us-gaap_DebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember" xlink:label="us-gaap_USStatesAndPoliticalSubdivisionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_USStatesAndPoliticalSubdivisionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="us-gaap_CorporateDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CorporateDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember" xlink:label="us-gaap_CommercialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CommercialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralizedDebtObligationsMember" xlink:label="us-gaap_CollateralizedDebtObligationsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CollateralizedDebtObligationsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherDebtSecuritiesMember" xlink:label="us-gaap_OtherDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_OtherDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentsOtherMember" xlink:label="pfg_InvestmentsOtherMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="pfg_InvestmentsOtherMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageBackedSecuritiesMember" xlink:label="us-gaap_MortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="us-gaap_MortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedMaturitiesMember" xlink:label="us-gaap_FixedMaturitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="us-gaap_FixedMaturitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeparateAccountAssetsMember" xlink:label="pfg_SeparateAccountAssetsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="pfg_SeparateAccountAssetsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511733933" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511733933" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AvailableForSaleSecurityMember" xlink:label="pfg_AvailableForSaleSecurityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_AvailableForSaleSecurityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="us-gaap_FairValueByLiabilityClassAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:to="us-gaap_FairValueByLiabilityClassAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByLiabilityClassAxis" xlink:to="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_639069372511739514" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByLiabilityClassAxis" xlink:to="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_639069372511739514" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentAndUniversalLifeContractsMember" xlink:label="pfg_InvestmentAndUniversalLifeContractsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="pfg_InvestmentAndUniversalLifeContractsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FundsWithheldPayableEmbeddedDerivativeMember" xlink:label="pfg_FundsWithheldPayableEmbeddedDerivativeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="pfg_FundsWithheldPayableEmbeddedDerivativeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:label="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:to="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:label="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:to="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueRecurringBasisUnobservableInputReconciliationAssetGainLossStatementOfIncomeExtensibleList" xlink:label="us-gaap_FairValueRecurringBasisUnobservableInputReconciliationAssetGainLossStatementOfIncomeExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1" xlink:to="us-gaap_FairValueRecurringBasisUnobservableInputReconciliationAssetGainLossStatementOfIncomeExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueRecurringBasisUnobservableInputReconciliationAssetGainLossStatementOfOtherComprehensiveIncomeExtensibleList" xlink:label="us-gaap_FairValueRecurringBasisUnobservableInputReconciliationAssetGainLossStatementOfOtherComprehensiveIncomeExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss" xlink:to="us-gaap_FairValueRecurringBasisUnobservableInputReconciliationAssetGainLossStatementOfOtherComprehensiveIncomeExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchasesSalesIssuancesSettlements" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchasesSalesIssuancesSettlements" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchasesSalesIssuancesSettlements" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarningsRelatingToPositionsStillHeld" xlink:label="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarningsRelatingToPositionsStillHeld" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarningsRelatingToPositionsStillHeld" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncome" xlink:label="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueRecurringBasisUnobservableInputReconciliationLiabilityGainLossStatementOfIncomeExtensibleList" xlink:label="us-gaap_FairValueRecurringBasisUnobservableInputReconciliationLiabilityGainLossStatementOfIncomeExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings" xlink:to="us-gaap_FairValueRecurringBasisUnobservableInputReconciliationLiabilityGainLossStatementOfIncomeExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchasesSalesIssuancesSettlements" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchasesSalesIssuancesSettlements" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchasesSalesIssuancesSettlements" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitiesGainLossIncludedInEarningsRelatingToPositionsStillHeld" xlink:label="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitiesGainLossIncludedInEarningsRelatingToPositionsStillHeld" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitiesGainLossIncludedInEarningsRelatingToPositionsStillHeld" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueRecurringBasisUnobservableInputReconciliationNetDerivativeAssetLiabilityGainLossStatementOfIncomeExtensibleList" xlink:label="us-gaap_FairValueRecurringBasisUnobservableInputReconciliationNetDerivativeAssetLiabilityGainLossStatementOfIncomeExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings" xlink:to="us-gaap_FairValueRecurringBasisUnobservableInputReconciliationNetDerivativeAssetLiabilityGainLossStatementOfIncomeExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchasesSalesIssuesSettlements" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchasesSalesIssuesSettlements" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="15" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchasesSalesIssuesSettlements" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersIntoLevel3" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersIntoLevel3" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="16" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersIntoLevel3" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="17" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisNetDerivativeAssetsLiabilitiesGainLossIncludedInEarningsRelatingToPositionsStillHeld" xlink:label="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisNetDerivativeAssetsLiabilitiesGainLossIncludedInEarningsRelatingToPositionsStillHeld" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="18" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisNetDerivativeAssetsLiabilitiesGainLossIncludedInEarningsRelatingToPositionsStillHeld" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitiesPurchasesSalesIssuancesSettlementsAbstract" xlink:label="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitiesPurchasesSalesIssuancesSettlementsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:to="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitiesPurchasesSalesIssuancesSettlementsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitiesPurchasesSalesIssuancesSettlementsAbstract" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitiesPurchasesSalesIssuancesSettlementsAbstract" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitiesPurchasesSalesIssuancesSettlementsAbstract" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitiesPurchasesSalesIssuancesSettlementsAbstract" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisIssuesNet" xlink:label="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisIssuesNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitiesPurchasesSalesIssuancesSettlementsAbstract" xlink:to="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisIssuesNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitiesPurchasesSalesIssuancesSettlementsAbstract" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitiesPurchasesSalesIssuancesSettlementsAbstract" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSales" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSales" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="pfg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitiesPurchasesSalesIssuancesSettlementsAbstract" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSales" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFairValueMeasurementsTransfersDetails" xlink:type="extended" xlink:title="99941803 - Disclosure - Fair Value Measurements - Transfers (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersTable" xlink:label="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511807994" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511807994" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AvailableForSaleSecurityMember" xlink:label="pfg_AvailableForSaleSecurityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_AvailableForSaleSecurityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="us-gaap_FairValueByAssetClassAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersTable" xlink:to="us-gaap_FairValueByAssetClassAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByAssetClassAxis" xlink:to="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_639069372511808445" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByAssetClassAxis" xlink:to="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_639069372511808445" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesMember" xlink:label="us-gaap_DebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="us-gaap_DebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember" xlink:label="us-gaap_USStatesAndPoliticalSubdivisionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_USStatesAndPoliticalSubdivisionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="us-gaap_CorporateDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CorporateDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralizedDebtObligationsMember" xlink:label="us-gaap_CollateralizedDebtObligationsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CollateralizedDebtObligationsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherDebtSecuritiesMember" xlink:label="us-gaap_OtherDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_OtherDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TradingSecuritiesMember" xlink:label="pfg_TradingSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="pfg_TradingSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="us-gaap_FairValueByMeasurementFrequencyAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersTable" xlink:to="us-gaap_FairValueByMeasurementFrequencyAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="us-gaap_FairValueMeasurementFrequencyDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain_639069372511819693" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="us-gaap_FairValueMeasurementFrequencyDomain_639069372511819693" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="us-gaap_FairValueMeasurementsRecurringMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueMeasurementFrequencyDomain" xlink:to="us-gaap_FairValueMeasurementsRecurringMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersLineItems" xlink:label="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersLineItems" xlink:to="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsLevel2ToLevel3TransfersAmount" xlink:label="pfg_FairValueAssetsLevel2ToLevel3TransfersAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersLineItems" xlink:to="pfg_FairValueAssetsLevel2ToLevel3TransfersAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueAssetsLevel3ToLevel2TransfersAmount" xlink:label="pfg_FairValueAssetsLevel3ToLevel2TransfersAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersLineItems" xlink:to="pfg_FairValueAssetsLevel3ToLevel2TransfersAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueNetDerivativeAssetLiabilityLevel2ToLevel3TransfersAmount" xlink:label="pfg_FairValueNetDerivativeAssetLiabilityLevel2ToLevel3TransfersAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersLineItems" xlink:to="pfg_FairValueNetDerivativeAssetLiabilityLevel2ToLevel3TransfersAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueNetDerivativeAssetLiabilityLevel3ToLevel2TransfersAmount" xlink:label="pfg_FairValueNetDerivativeAssetLiabilityLevel3ToLevel2TransfersAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTransfersLineItems" xlink:to="pfg_FairValueNetDerivativeAssetLiabilityLevel3ToLevel2TransfersAmount" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFairValueMeasurementsQuantitativeInformationForLevel3MeasurementsDetails" xlink:type="extended" xlink:title="99941804 - Disclosure - Fair Value Measurements - Quantitative Information for Level 3 Measurements (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueInputsQuantitativeInformationTable" xlink:label="pfg_FairValueInputsQuantitativeInformationTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="us-gaap_FairValueByMeasurementFrequencyAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_FairValueInputsQuantitativeInformationTable" xlink:to="us-gaap_FairValueByMeasurementFrequencyAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="us-gaap_FairValueMeasurementFrequencyDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain_639069372511831005" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="us-gaap_FairValueMeasurementFrequencyDomain_639069372511831005" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="us-gaap_FairValueMeasurementsRecurringMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueMeasurementFrequencyDomain" xlink:to="us-gaap_FairValueMeasurementsRecurringMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_FairValueInputsQuantitativeInformationTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_639069372511836714" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_639069372511836714" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="us-gaap_FairValueInputsLevel3Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel3Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="us-gaap_FairValueByAssetClassAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="pfg_FairValueInputsQuantitativeInformationTable" xlink:to="us-gaap_FairValueByAssetClassAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByAssetClassAxis" xlink:to="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_639069372511842360" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByAssetClassAxis" xlink:to="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_639069372511842360" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesMember" xlink:label="us-gaap_DebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="us-gaap_DebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember" xlink:label="us-gaap_CorporateDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CorporateDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherDebtSecuritiesMember" xlink:label="us-gaap_OtherDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_OtherDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentsOtherMember" xlink:label="pfg_InvestmentsOtherMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="pfg_InvestmentsOtherMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeparateAccountAssetsMember" xlink:label="pfg_SeparateAccountAssetsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="pfg_SeparateAccountAssetsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="us-gaap_FairValueByLiabilityClassAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="pfg_FairValueInputsQuantitativeInformationTable" xlink:to="us-gaap_FairValueByLiabilityClassAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByLiabilityClassAxis" xlink:to="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_639069372511847987" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByLiabilityClassAxis" xlink:to="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_639069372511847987" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentAndUniversalLifeContractsMember" xlink:label="pfg_InvestmentAndUniversalLifeContractsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="pfg_InvestmentAndUniversalLifeContractsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="5" xlink:from="pfg_FairValueInputsQuantitativeInformationTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511853606" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511853606" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AvailableForSaleSecurityMember" xlink:label="pfg_AvailableForSaleSecurityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_AvailableForSaleSecurityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TradingSecuritiesMember" xlink:label="pfg_TradingSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_TradingSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ValuationTechniqueAxis" xlink:label="us-gaap_ValuationTechniqueAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="6" xlink:from="pfg_FairValueInputsQuantitativeInformationTable" xlink:to="us-gaap_ValuationTechniqueAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="us-gaap_ValuationTechniqueDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_ValuationTechniqueAxis" xlink:to="us-gaap_ValuationTechniqueDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="us-gaap_ValuationTechniqueDomain_639069372511859238" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_ValuationTechniqueAxis" xlink:to="us-gaap_ValuationTechniqueDomain_639069372511859238" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ValuationTechniqueDiscountedCashFlowMember" xlink:label="us-gaap_ValuationTechniqueDiscountedCashFlowMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ValuationTechniqueDomain" xlink:to="us-gaap_ValuationTechniqueDiscountedCashFlowMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DiscountedCashFlowRealEstateMember" xlink:label="pfg_DiscountedCashFlowRealEstateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ValuationTechniqueDomain" xlink:to="pfg_DiscountedCashFlowRealEstateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DiscountedCashFlowRealEstateDebtMember" xlink:label="pfg_DiscountedCashFlowRealEstateDebtMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ValuationTechniqueDomain" xlink:to="pfg_DiscountedCashFlowRealEstateDebtMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeAxis" xlink:label="us-gaap_MeasurementInputTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="7" xlink:from="pfg_FairValueInputsQuantitativeInformationTable" xlink:to="us-gaap_MeasurementInputTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="us-gaap_MeasurementInputTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_MeasurementInputTypeAxis" xlink:to="us-gaap_MeasurementInputTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="us-gaap_MeasurementInputTypeDomain_639069372511870489" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_MeasurementInputTypeAxis" xlink:to="us-gaap_MeasurementInputTypeDomain_639069372511870489" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputDiscountRateMember" xlink:label="us-gaap_MeasurementInputDiscountRateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="us-gaap_MeasurementInputDiscountRateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputEbitdaMultipleMember" xlink:label="us-gaap_MeasurementInputEbitdaMultipleMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="us-gaap_MeasurementInputEbitdaMultipleMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputDiscountForLackOfMarketabilityMember" xlink:label="us-gaap_MeasurementInputDiscountForLackOfMarketabilityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="us-gaap_MeasurementInputDiscountForLackOfMarketabilityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputComparabilityAdjustmentMember" xlink:label="us-gaap_MeasurementInputComparabilityAdjustmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="us-gaap_MeasurementInputComparabilityAdjustmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputDefaultRateMember" xlink:label="us-gaap_MeasurementInputDefaultRateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="us-gaap_MeasurementInputDefaultRateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputLossSeverityMember" xlink:label="us-gaap_MeasurementInputLossSeverityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="us-gaap_MeasurementInputLossSeverityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MeasurementInputTerminalCapitalizationRateMember" xlink:label="pfg_MeasurementInputTerminalCapitalizationRateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="pfg_MeasurementInputTerminalCapitalizationRateMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputLongTermRevenueGrowthRateMember" xlink:label="us-gaap_MeasurementInputLongTermRevenueGrowthRateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="us-gaap_MeasurementInputLongTermRevenueGrowthRateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MeasurementInputLoanToValueRatioMember" xlink:label="pfg_MeasurementInputLoanToValueRatioMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="pfg_MeasurementInputLoanToValueRatioMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MeasurementInputMarketInterestRateMember" xlink:label="pfg_MeasurementInputMarketInterestRateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="pfg_MeasurementInputMarketInterestRateMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MeasurementInputLongDurationInterestRateMember" xlink:label="pfg_MeasurementInputLongDurationInterestRateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="pfg_MeasurementInputLongDurationInterestRateMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputPriceVolatilityMember" xlink:label="us-gaap_MeasurementInputPriceVolatilityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="us-gaap_MeasurementInputPriceVolatilityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MeasurementInputNonPerformanceRiskMember" xlink:label="pfg_MeasurementInputNonPerformanceRiskMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="pfg_MeasurementInputNonPerformanceRiskMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputLapseRateMember" xlink:label="us-gaap_MeasurementInputLapseRateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="us-gaap_MeasurementInputTypeDomain" xlink:to="us-gaap_MeasurementInputLapseRateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="8" xlink:from="pfg_FairValueInputsQuantitativeInformationTable" xlink:to="srt_RangeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639069372511898570" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_639069372511898570" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_WeightedAverageMember" xlink:label="srt_WeightedAverageMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_RangeMember" xlink:to="srt_WeightedAverageMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:label="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:to="pfg_FairValueInputsQuantitativeInformationTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="us-gaap_AssetsFairValueDisclosure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:to="us-gaap_AssetsFairValueDisclosure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="us-gaap_LiabilitiesFairValueDisclosure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:to="us-gaap_LiabilitiesFairValueDisclosure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleValuationTechniqueExtensibleList" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleValuationTechniqueExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleValuationTechniqueExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesTradingValuationTechniqueExtensibleList" xlink:label="us-gaap_DebtSecuritiesTradingValuationTechniqueExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:to="us-gaap_DebtSecuritiesTradingValuationTechniqueExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesTradingMeasurementInput" xlink:label="us-gaap_DebtSecuritiesTradingMeasurementInput" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:to="us-gaap_DebtSecuritiesTradingMeasurementInput" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherInvestmentsMeasurementInput" xlink:label="pfg_OtherInvestmentsMeasurementInput" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:to="pfg_OtherInvestmentsMeasurementInput" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeparateAccountAssetsMeasurementInput" xlink:label="pfg_SeparateAccountAssetsMeasurementInput" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:to="pfg_SeparateAccountAssetsMeasurementInput" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmbeddedDerivativeLiabilityValuationTechniqueExtensibleList" xlink:label="us-gaap_EmbeddedDerivativeLiabilityValuationTechniqueExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:to="us-gaap_EmbeddedDerivativeLiabilityValuationTechniqueExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmbeddedDerivativeLiabilityMeasurementInput" xlink:label="us-gaap_EmbeddedDerivativeLiabilityMeasurementInput" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="pfg_FairValueInputsAssetsLiabilitiesQuantitativeInformationLineItems" xlink:to="us-gaap_EmbeddedDerivativeLiabilityMeasurementInput" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFairValueMeasurementsFairValueOptionOnConsolidatedViesDetails" xlink:type="extended" xlink:title="99941805 - Disclosure - Fair Value Measurements - Fair Value Option on Consolidated VIEs (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionQuantitativeDisclosuresTable" xlink:label="us-gaap_FairValueOptionQuantitativeDisclosuresTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511937368" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372511937368" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageBackedSecuritiesMember" xlink:label="us-gaap_MortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_MortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CertainOtherLoansMember" xlink:label="pfg_CertainOtherLoansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_CertainOtherLoansMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CertainOtherLoansOfConsolidatedVariableInterestEntityMember" xlink:label="pfg_CertainOtherLoansOfConsolidatedVariableInterestEntityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_CertainOtherLoansOfConsolidatedVariableInterestEntityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BorrowingsMember" xlink:label="us-gaap_BorrowingsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="us-gaap_BorrowingsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis" xlink:label="srt_ConsolidatedEntitiesAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresTable" xlink:to="srt_ConsolidatedEntitiesAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain_639069372511943542" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain_639069372511943542" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:label="us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidatedEntitiesDomain" xlink:to="us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionQuantitativeDisclosuresLineItems" xlink:label="us-gaap_FairValueOptionQuantitativeDisclosuresLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresLineItems" xlink:to="us-gaap_FairValueOptionQuantitativeDisclosuresTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueOptionFairValueOfAssetsForWhichFairValueOptionWasElected" xlink:label="pfg_FairValueOptionFairValueOfAssetsForWhichFairValueOptionWasElected" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresLineItems" xlink:to="pfg_FairValueOptionFairValueOfAssetsForWhichFairValueOptionWasElected" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueOptionContractualPrincipalAmountsOfAssetsForWhichFairValueOptionWasElected" xlink:label="pfg_FairValueOptionContractualPrincipalAmountsOfAssetsForWhichFairValueOptionWasElected" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresLineItems" xlink:to="pfg_FairValueOptionContractualPrincipalAmountsOfAssetsForWhichFairValueOptionWasElected" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueOptionFairValueOfLiabilitiesForWhichFairValueOptionWasElected" xlink:label="pfg_FairValueOptionFairValueOfLiabilitiesForWhichFairValueOptionWasElected" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresLineItems" xlink:to="pfg_FairValueOptionFairValueOfLiabilitiesForWhichFairValueOptionWasElected" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FairValueOptionContractualPrincipalAmountsOfLiabilitiesForWhichFairValueOptionWasElected" xlink:label="pfg_FairValueOptionContractualPrincipalAmountsOfLiabilitiesForWhichFairValueOptionWasElected" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresLineItems" xlink:to="pfg_FairValueOptionContractualPrincipalAmountsOfLiabilitiesForWhichFairValueOptionWasElected" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionCreditRiskGainsLossesOnAssets" xlink:label="us-gaap_FairValueOptionCreditRiskGainsLossesOnAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresLineItems" xlink:to="us-gaap_FairValueOptionCreditRiskGainsLossesOnAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionChangesInFairValueGainLoss1" xlink:label="us-gaap_FairValueOptionChangesInFairValueGainLoss1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresLineItems" xlink:to="us-gaap_FairValueOptionChangesInFairValueGainLoss1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeOperating" xlink:label="us-gaap_InterestIncomeOperating" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresLineItems" xlink:to="us-gaap_InterestIncomeOperating" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureFairValueMeasurementsFinancialInstrumentsNotReportedAtFairValueDetails" xlink:type="extended" xlink:title="99941806 - Disclosure - Fair Value Measurements - Financial Instruments Not Reported at Fair Value (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialInstrumentsNotReportedAtFairValueTable" xlink:label="pfg_FinancialInstrumentsNotReportedAtFairValueTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementBasisAxis" xlink:label="us-gaap_FairValueByMeasurementBasisAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_FinancialInstrumentsNotReportedAtFairValueTable" xlink:to="us-gaap_FairValueByMeasurementBasisAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:label="us-gaap_PortionAtFairValueFairValueDisclosureMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByMeasurementBasisAxis" xlink:to="us-gaap_PortionAtFairValueFairValueDisclosureMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:label="us-gaap_PortionAtFairValueFairValueDisclosureMember_639069372511960399" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByMeasurementBasisAxis" xlink:to="us-gaap_PortionAtFairValueFairValueDisclosureMember_639069372511960399" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember" xlink:label="us-gaap_CarryingReportedAmountFairValueDisclosureMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:to="us-gaap_CarryingReportedAmountFairValueDisclosureMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:label="us-gaap_EstimateOfFairValueFairValueDisclosureMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:to="us-gaap_EstimateOfFairValueFairValueDisclosureMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_FinancialInstrumentsNotReportedAtFairValueTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_639069372512004934" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_639069372512004934" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="us-gaap_FairValueInputsLevel1Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel1Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="us-gaap_FairValueInputsLevel2Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="us-gaap_FairValueInputsLevel3Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel3Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FinancialInstrumentsNotReportedAtFairValueLineItems" xlink:label="pfg_FinancialInstrumentsNotReportedAtFairValueLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_FinancialInstrumentsNotReportedAtFairValueLineItems" xlink:to="pfg_FinancialInstrumentsNotReportedAtFairValueTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:label="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_FinancialInstrumentsNotReportedAtFairValueLineItems" xlink:to="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" xlink:label="us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LoansInsurancePolicy" xlink:label="us-gaap_LoansInsurancePolicy" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="us-gaap_LoansInsurancePolicy" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherInvestmentsFairValueDisclosure" xlink:label="pfg_OtherInvestmentsFairValueDisclosure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="pfg_OtherInvestmentsFairValueDisclosure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CashAndCashEquivalentFairValueDisclosure" xlink:label="pfg_CashAndCashEquivalentFairValueDisclosure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="pfg_CashAndCashEquivalentFairValueDisclosure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ReinsuranceDepositReceivable" xlink:label="pfg_ReinsuranceDepositReceivable" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="pfg_ReinsuranceDepositReceivable" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CashCollateralReceivable" xlink:label="pfg_CashCollateralReceivable" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="pfg_CashCollateralReceivable" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentContractsFairValueDisclosure" xlink:label="pfg_InvestmentContractsFairValueDisclosure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="pfg_InvestmentContractsFairValueDisclosure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermBorrowings" xlink:label="us-gaap_ShortTermBorrowings" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="us-gaap_ShortTermBorrowings" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt" xlink:label="us-gaap_LongTermDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="us-gaap_LongTermDebt" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SeparateAccountLiabilitiesFairValueDisclosure" xlink:label="pfg_SeparateAccountLiabilitiesFairValueDisclosure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="pfg_SeparateAccountLiabilitiesFairValueDisclosure" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Deposits" xlink:label="us-gaap_Deposits" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="us-gaap_Deposits" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CashCollateralLiabilityFairValueDisclosure" xlink:label="pfg_CashCollateralLiabilityFairValueDisclosure" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract" xlink:to="pfg_CashCollateralLiabilityFairValueDisclosure" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureStatutoryInsuranceFinancialInformationDetails" xlink:type="extended" xlink:title="99941901 - Disclosure - Statutory Insurance Financial Information (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatutoryAccountingPracticesTable" xlink:label="us-gaap_StatutoryAccountingPracticesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_StatutoryAccountingPracticesTable" xlink:to="dei_LegalEntityAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_639069372512031536" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_639069372512031536" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_BermudaReinsurerMember" xlink:label="pfg_BermudaReinsurerMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="dei_EntityDomain" xlink:to="pfg_BermudaReinsurerMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatutoryAccountingPracticesLineItems" xlink:label="us-gaap_StatutoryAccountingPracticesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_StatutoryAccountingPracticesLineItems" xlink:to="us-gaap_StatutoryAccountingPracticesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StatutoryAccountingPracticesStatutoryNetIncomeAndSurplusAbstract" xlink:label="pfg_StatutoryAccountingPracticesStatutoryNetIncomeAndSurplusAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_StatutoryAccountingPracticesLineItems" xlink:to="pfg_StatutoryAccountingPracticesStatutoryNetIncomeAndSurplusAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StatutoryReservesAssumedByAffiliatedReinsuranceSubsidiaries" xlink:label="pfg_StatutoryReservesAssumedByAffiliatedReinsuranceSubsidiaries" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_StatutoryAccountingPracticesStatutoryNetIncomeAndSurplusAbstract" xlink:to="pfg_StatutoryReservesAssumedByAffiliatedReinsuranceSubsidiaries" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AdmittedAssetsUnderPrescribedAndPermittedStatutoryAccountingPractices" xlink:label="pfg_AdmittedAssetsUnderPrescribedAndPermittedStatutoryAccountingPractices" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_StatutoryAccountingPracticesStatutoryNetIncomeAndSurplusAbstract" xlink:to="pfg_AdmittedAssetsUnderPrescribedAndPermittedStatutoryAccountingPractices" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StatutoryAccountingPracticesStatutoryNetIncomeAmountIncreaseDecreaseDueToReinsuranceReportingPractices" xlink:label="pfg_StatutoryAccountingPracticesStatutoryNetIncomeAmountIncreaseDecreaseDueToReinsuranceReportingPractices" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_StatutoryAccountingPracticesStatutoryNetIncomeAndSurplusAbstract" xlink:to="pfg_StatutoryAccountingPracticesStatutoryNetIncomeAmountIncreaseDecreaseDueToReinsuranceReportingPractices" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StatutoryAccountingPracticesStatutoryCapitalAndSurplusRequiredIncreaseDecreaseDueToReinsuranceReportingPractices" xlink:label="pfg_StatutoryAccountingPracticesStatutoryCapitalAndSurplusRequiredIncreaseDecreaseDueToReinsuranceReportingPractices" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_StatutoryAccountingPracticesStatutoryNetIncomeAndSurplusAbstract" xlink:to="pfg_StatutoryAccountingPracticesStatutoryCapitalAndSurplusRequiredIncreaseDecreaseDueToReinsuranceReportingPractices" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InsuranceCededOutOfUlsgReservesByAffiliatedReinsuranceSubsidiaries" xlink:label="pfg_InsuranceCededOutOfUlsgReservesByAffiliatedReinsuranceSubsidiaries" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_StatutoryAccountingPracticesStatutoryNetIncomeAndSurplusAbstract" xlink:to="pfg_InsuranceCededOutOfUlsgReservesByAffiliatedReinsuranceSubsidiaries" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatutoryAccountingPracticesStatutoryNetIncomeAmount" xlink:label="us-gaap_StatutoryAccountingPracticesStatutoryNetIncomeAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_StatutoryAccountingPracticesStatutoryNetIncomeAndSurplusAbstract" xlink:to="us-gaap_StatutoryAccountingPracticesStatutoryNetIncomeAmount" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSegmentInformationReconciliationOfSegmentAssetsToConsolidatedDetails" xlink:type="extended" xlink:title="99942002 - Disclosure - Segment Information - Reconciliation of Segment Assets to Consolidated (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable" xlink:label="us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372512048310" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372512048310" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingAssetReconcilingItemLineItems" xlink:label="us-gaap_SegmentReportingAssetReconcilingItemLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SegmentReportingAssetReconcilingItemLineItems" xlink:to="us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentReportingAssetReconcilingItemLineItems" xlink:to="us-gaap_Assets" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSegmentInformationReconciliationOfSegmentOperatingRevenuesConsolidatedDetails" xlink:type="extended" xlink:title="99942003 - Disclosure - Segment Information - Reconciliation of Segment Operating Revenues Consolidated (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ReconciliationOfOperatingRevenueAndProfitLossFromSegmentsToConsolidatedTable" xlink:label="pfg_ReconciliationOfOperatingRevenueAndProfitLossFromSegmentsToConsolidatedTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_ReconciliationOfOperatingRevenueAndProfitLossFromSegmentsToConsolidatedTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512059522" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512059522" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember" xlink:label="us-gaap_OperatingSegmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:label="us-gaap_MaterialReconcilingItemsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_MaterialReconcilingItemsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntersegmentEliminationMember" xlink:label="us-gaap_IntersegmentEliminationMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_IntersegmentEliminationMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="pfg_ReconciliationOfOperatingRevenueAndProfitLossFromSegmentsToConsolidatedTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372512065085" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372512065085" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:label="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_ReconciliationOfOperatingRevenueAndProfitLossFromSegmentsToConsolidatedTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_RevenueFromContractsWithCustomers" xlink:label="pfg_RevenueFromContractsWithCustomers" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_RevenueFromContractsWithCustomers" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AdjustmentForRevenueFromContractWithCustomerExcludedInOperatingRevenues" xlink:label="pfg_AdjustmentForRevenueFromContractWithCustomerExcludedInOperatingRevenues" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_AdjustmentForRevenueFromContractWithCustomerExcludedInOperatingRevenues" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetInvestmentIncomeIncludedInOperatingRevenues" xlink:label="pfg_NetInvestmentIncomeIncludedInOperatingRevenues" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_NetInvestmentIncomeIncludedInOperatingRevenues" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeLossFromEquityMethodInvestmentsInOperatingRevenues" xlink:label="pfg_IncomeLossFromEquityMethodInvestmentsInOperatingRevenues" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_IncomeLossFromEquityMethodInvestmentsInOperatingRevenues" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InterSegmentRevenue" xlink:label="pfg_InterSegmentRevenue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_InterSegmentRevenue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportingInformationNetRealizedCapitalGainsLosses" xlink:label="pfg_SegmentReportingInformationNetRealizedCapitalGainsLosses" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_SegmentReportingInformationNetRealizedCapitalGainsLosses" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_RevenueFromExitedBusiness" xlink:label="pfg_RevenueFromExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_RevenueFromExitedBusiness" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportingInformationRevenueAdjustmentsRelatedToEquityMethodInvestments" xlink:label="pfg_SegmentReportingInformationRevenueAdjustmentsRelatedToEquityMethodInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_SegmentReportingInformationRevenueAdjustmentsRelatedToEquityMethodInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportInformationMarketRiskBenefitDerivativeSettlements" xlink:label="pfg_SegmentReportInformationMarketRiskBenefitDerivativeSettlements" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_SegmentReportInformationMarketRiskBenefitDerivativeSettlements" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues" xlink:label="us-gaap_Revenues" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="us-gaap_Revenues" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSegmentInformationRevenuesFromExitedBusinessDetails" xlink:type="extended" xlink:title="99942004 - Disclosure - Segment Information - Revenues from exited business (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ReconciliationOfOperatingRevenueAndProfitLossFromSegmentsToConsolidatedTable" xlink:label="pfg_ReconciliationOfOperatingRevenueAndProfitLossFromSegmentsToConsolidatedTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="pfg_ReconciliationOfOperatingRevenueAndProfitLossFromSegmentsToConsolidatedTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512081837" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512081837" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:label="us-gaap_MaterialReconcilingItemsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_MaterialReconcilingItemsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:label="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_ReconciliationOfOperatingRevenueAndProfitLossFromSegmentsToConsolidatedTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_RevenuesFromExitedBusinessAbstract" xlink:label="pfg_RevenuesFromExitedBusinessAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_OperatingRevenueAndProfitLossFromSegmentsToConsolidatedLineItems" xlink:to="pfg_RevenuesFromExitedBusinessAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivative" xlink:label="pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivative" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_RevenuesFromExitedBusinessAbstract" xlink:to="pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivative" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GainLossOnFundsWithheldAssets" xlink:label="pfg_GainLossOnFundsWithheldAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_RevenuesFromExitedBusinessAbstract" xlink:to="pfg_GainLossOnFundsWithheldAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AmortizationOfReinsuranceGain" xlink:label="pfg_AmortizationOfReinsuranceGain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_RevenuesFromExitedBusinessAbstract" xlink:to="pfg_AmortizationOfReinsuranceGain" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherImpactsOfExitedBusiness" xlink:label="pfg_OtherImpactsOfExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_RevenuesFromExitedBusinessAbstract" xlink:to="pfg_OtherImpactsOfExitedBusiness" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_RevenueFromExitedBusiness" xlink:label="pfg_RevenueFromExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_RevenuesFromExitedBusinessAbstract" xlink:to="pfg_RevenueFromExitedBusiness" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSegmentInformationReconciliationOfSegmentExpensesDetails" xlink:type="extended" xlink:title="99942005 - Disclosure - Segment Information - Reconciliation of Segment Expenses (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:label="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512093237" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512093237" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember" xlink:label="us-gaap_OperatingSegmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:label="us-gaap_MaterialReconcilingItemsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_MaterialReconcilingItemsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372512098817" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372512098817" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:label="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" xlink:label="us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitRemeasurementGainLoss" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitRemeasurementGainLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitRemeasurementGainLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitChangeInFairValueGainLoss" xlink:label="us-gaap_MarketRiskBenefitChangeInFairValueGainLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_MarketRiskBenefitChangeInFairValueGainLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderDividends" xlink:label="us-gaap_PolicyholderDividends" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_PolicyholderDividends" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoninterestExpenseCommissionExpense" xlink:label="us-gaap_NoninterestExpenseCommissionExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_NoninterestExpenseCommissionExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredPolicyAcquisitionCostAndCapitalizedContractCostAdditions" xlink:label="pfg_DeferredPolicyAcquisitionCostAndCapitalizedContractCostAdditions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_DeferredPolicyAcquisitionCostAndCapitalizedContractCostAdditions" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredPolicyAcquisitionCostAndCapitalizedContractCostAmortizationExpense" xlink:label="pfg_DeferredPolicyAcquisitionCostAndCapitalizedContractCostAmortizationExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_DeferredPolicyAcquisitionCostAndCapitalizedContractCostAmortizationExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentDepreciationAndAmortizationExpense" xlink:label="pfg_SegmentDepreciationAndAmortizationExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_SegmentDepreciationAndAmortizationExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseDebt" xlink:label="us-gaap_InterestExpenseDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_InterestExpenseDebt" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportingCompensationAndOtherSegmentItemAmount" xlink:label="pfg_SegmentReportingCompensationAndOtherSegmentItemAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_SegmentReportingCompensationAndOtherSegmentItemAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" xlink:label="pfg_OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentExpenses" xlink:label="pfg_SegmentExpenses" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_SegmentExpenses" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportingInformationNetRealizedCapitalGainsLossesExpenseAdjustments" xlink:label="pfg_SegmentReportingInformationNetRealizedCapitalGainsLossesExpenseAdjustments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_SegmentReportingInformationNetRealizedCapitalGainsLossesExpenseAdjustments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportInformationMarketRiskBenefitDerivativeSettlements" xlink:label="pfg_SegmentReportInformationMarketRiskBenefitDerivativeSettlements" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="15" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_SegmentReportInformationMarketRiskBenefitDerivativeSettlements" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ExpensesFromExitedBusiness" xlink:label="pfg_ExpensesFromExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="16" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_ExpensesFromExitedBusiness" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BenefitsLossesAndExpenses" xlink:label="us-gaap_BenefitsLossesAndExpenses" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="17" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_BenefitsLossesAndExpenses" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSegmentInformationExpensesFromExitedBusinessDetails" xlink:type="extended" xlink:title="99942006 - Disclosure - Segment Information - Expenses from exited business (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:label="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512132199" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512132199" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:label="us-gaap_MaterialReconcilingItemsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_MaterialReconcilingItemsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:label="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ExpensesFromExitedBusinessAbstract" xlink:label="pfg_ExpensesFromExitedBusinessAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_ExpensesFromExitedBusinessAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AmortizationExpensesOfReinsuranceGainsLossesExitedBusiness" xlink:label="pfg_AmortizationExpensesOfReinsuranceGainsLossesExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_ExpensesFromExitedBusinessAbstract" xlink:to="pfg_AmortizationExpensesOfReinsuranceGainsLossesExitedBusiness" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherImpactsOnExpensesOfExitedBusiness" xlink:label="pfg_OtherImpactsOnExpensesOfExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_ExpensesFromExitedBusinessAbstract" xlink:to="pfg_OtherImpactsOnExpensesOfExitedBusiness" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ExpensesFromExitedBusiness" xlink:label="pfg_ExpensesFromExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_ExpensesFromExitedBusinessAbstract" xlink:to="pfg_ExpensesFromExitedBusiness" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSegmentInformationSegmentPreTaxOperatingEarningsDetails" xlink:type="extended" xlink:title="99942007 - Disclosure - Segment Information - Segment Pre-Tax Operating Earnings (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" xlink:label="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512143359" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512143359" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember" xlink:label="us-gaap_OperatingSegmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:label="us-gaap_MaterialReconcilingItemsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_MaterialReconcilingItemsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372512143359" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372512143359" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:label="us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:to="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportingInformationPretaxNetRealizedCapitalGainsLossesNetOfAdjustments" xlink:label="pfg_SegmentReportingInformationPretaxNetRealizedCapitalGainsLossesNetOfAdjustments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:to="pfg_SegmentReportingInformationPretaxNetRealizedCapitalGainsLossesNetOfAdjustments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PretaxIncomeFromExitedBusiness" xlink:label="pfg_PretaxIncomeFromExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:to="pfg_PretaxIncomeFromExitedBusiness" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportingInformationEarningsAdjustmentsRelatedToEquityMethodInvestmentsAndNoncontrollingInterest" xlink:label="pfg_SegmentReportingInformationEarningsAdjustmentsRelatedToEquityMethodInvestmentsAndNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:to="pfg_SegmentReportingInformationEarningsAdjustmentsRelatedToEquityMethodInvestmentsAndNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeLossFromContinuingOperationsBeforeIncomeTaxes" xlink:label="pfg_IncomeLossFromContinuingOperationsBeforeIncomeTaxes" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:to="pfg_IncomeLossFromContinuingOperationsBeforeIncomeTaxes" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSegmentInformationPreTaxNetRealizedCapitalGainsLossesDetails" xlink:type="extended" xlink:title="99942008 - Disclosure - Segment Information - Pre-tax net Realized Capital Gains (Losses) (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:label="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512160073" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512160073" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:label="us-gaap_MaterialReconcilingItemsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_MaterialReconcilingItemsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:label="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:label="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnInvestments" xlink:label="us-gaap_GainLossOnInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="us-gaap_GainLossOnInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeAndHedgingRelatedAdjustments" xlink:label="pfg_DerivativeAndHedgingRelatedAdjustments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_DerivativeAndHedgingRelatedAdjustments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MarketValueAdjustmentsFeeRevenues" xlink:label="pfg_MarketValueAdjustmentsFeeRevenues" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_MarketValueAdjustmentsFeeRevenues" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CertainVariableAnnuityFees" xlink:label="pfg_CertainVariableAnnuityFees" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_CertainVariableAnnuityFees" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EquityMethodInvestmentsRelatedAdjustments" xlink:label="pfg_EquityMethodInvestmentsRelatedAdjustments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_EquityMethodInvestmentsRelatedAdjustments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SponsoredInvestmentFundsRelatedAndOtherAdjustments" xlink:label="pfg_SponsoredInvestmentFundsRelatedAndOtherAdjustments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_SponsoredInvestmentFundsRelatedAndOtherAdjustments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportingInformationNetRealizedCapitalGainsLosses" xlink:label="pfg_SegmentReportingInformationNetRealizedCapitalGainsLosses" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_SegmentReportingInformationNetRealizedCapitalGainsLosses" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DeferredAcquisitionCostAndOtherActuarialBalancesAmortizationExpense" xlink:label="pfg_DeferredAcquisitionCostAndOtherActuarialBalancesAmortizationExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_DeferredAcquisitionCostAndOtherActuarialBalancesAmortizationExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CapitalGainsLossesDistributed" xlink:label="pfg_CapitalGainsLossesDistributed" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_CapitalGainsLossesDistributed" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DerivativeAndHedgingRelatedExpenseAdjustments" xlink:label="pfg_DerivativeAndHedgingRelatedExpenseAdjustments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_DerivativeAndHedgingRelatedExpenseAdjustments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MarketValueAdjustmentOfMarketRiskBenefits" xlink:label="pfg_MarketValueAdjustmentOfMarketRiskBenefits" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_MarketValueAdjustmentOfMarketRiskBenefits" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MarketValueAdjustmentsEmbeddedDerivatives" xlink:label="pfg_MarketValueAdjustmentsEmbeddedDerivatives" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_MarketValueAdjustmentsEmbeddedDerivatives" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportingInformationNetRealizedCapitalGainsLossesNetOfExpenseAdjustments" xlink:label="pfg_SegmentReportingInformationNetRealizedCapitalGainsLossesNetOfExpenseAdjustments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_SegmentReportingInformationNetRealizedCapitalGainsLossesNetOfExpenseAdjustments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportingInformationPretaxNetRealizedCapitalGainsLossesNetOfAdjustments" xlink:label="pfg_SegmentReportingInformationPretaxNetRealizedCapitalGainsLossesNetOfAdjustments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="pfg_ReconciliationOfNetRealizedCapitalGainsLossesAbstract" xlink:to="pfg_SegmentReportingInformationPretaxNetRealizedCapitalGainsLossesNetOfAdjustments" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSegmentInformationPreTaxIncomeLossFromExitedBusinessDetails" xlink:type="extended" xlink:title="99942009 - Disclosure - Segment Information - Pre-tax income (loss) from exited business (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" xlink:label="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512181970" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512181970" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:label="us-gaap_MaterialReconcilingItemsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_MaterialReconcilingItemsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:label="us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:to="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PreTaxIncomeLossFromExitedBusinessAbstract" xlink:label="pfg_PreTaxIncomeLossFromExitedBusinessAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:to="pfg_PreTaxIncomeLossFromExitedBusinessAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivative" xlink:label="pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivative" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_PreTaxIncomeLossFromExitedBusinessAbstract" xlink:to="pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivative" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GainLossOnFundsWithheldAssets" xlink:label="pfg_GainLossOnFundsWithheldAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_PreTaxIncomeLossFromExitedBusinessAbstract" xlink:to="pfg_GainLossOnFundsWithheldAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AmortizationOfReinsuranceGainLoss" xlink:label="pfg_AmortizationOfReinsuranceGainLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_PreTaxIncomeLossFromExitedBusinessAbstract" xlink:to="pfg_AmortizationOfReinsuranceGainLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherImpactsOfExitedBusinessPreTaxIncomeLoss" xlink:label="pfg_OtherImpactsOfExitedBusinessPreTaxIncomeLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_PreTaxIncomeLossFromExitedBusinessAbstract" xlink:to="pfg_OtherImpactsOfExitedBusinessPreTaxIncomeLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PretaxIncomeFromExitedBusiness" xlink:label="pfg_PretaxIncomeFromExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="pfg_PreTaxIncomeLossFromExitedBusinessAbstract" xlink:to="pfg_PretaxIncomeFromExitedBusiness" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSegmentInformationIncomeTaxExpenseBenefitBySegmentDetails" xlink:type="extended" xlink:title="99942010 - Disclosure - Segment Information - Income Tax Expense (Benefit) by Segment (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:label="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372512193589" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372512193589" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512199163" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512199163" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember" xlink:label="us-gaap_OperatingSegmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:label="us-gaap_MaterialReconcilingItemsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_MaterialReconcilingItemsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:label="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetRealizedCapitalGainsLossesIncomeTaxes" xlink:label="pfg_NetRealizedCapitalGainsLossesIncomeTaxes" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_NetRealizedCapitalGainsLossesIncomeTaxes" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeTaxFromExitedBusiness" xlink:label="pfg_IncomeTaxFromExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_IncomeTaxFromExitedBusiness" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentReportingInformationTaxExpenseBenefitAssociatedWithCertainAdjustmentsRelatedToEquityMethodInvestmentsAndNoncontrollingInterest" xlink:label="pfg_SegmentReportingInformationTaxExpenseBenefitAssociatedWithCertainAdjustmentsRelatedToEquityMethodInvestmentsAndNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_SegmentReportingInformationTaxExpenseBenefitAssociatedWithCertainAdjustmentsRelatedToEquityMethodInvestmentsAndNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_IncomeTaxExpenseBenefit" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSegmentInformationIncomeTaxExpenseBenefitRelatedToExitedBusinessDetails" xlink:type="extended" xlink:title="99942011 - Disclosure - Segment Information - Income Tax Expense (Benefit) Related to Exited Business (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:label="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512209917" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512209917" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:label="us-gaap_MaterialReconcilingItemsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_MaterialReconcilingItemsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:label="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivativeTax" xlink:label="pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivativeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_ChangeInFairValueOfFundsWithheldEmbeddedDerivativeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_GainLossOnFundsWithheldAssetsTax" xlink:label="pfg_GainLossOnFundsWithheldAssetsTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_GainLossOnFundsWithheldAssetsTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeTaxExpensesBenefitsGlobalIntangibleLowTaxedIncomeAllocatedToExitedBusiness" xlink:label="pfg_IncomeTaxExpensesBenefitsGlobalIntangibleLowTaxedIncomeAllocatedToExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_IncomeTaxExpensesBenefitsGlobalIntangibleLowTaxedIncomeAllocatedToExitedBusiness" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AmortizationOfReinsuranceGainLossTax" xlink:label="pfg_AmortizationOfReinsuranceGainLossTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_AmortizationOfReinsuranceGainLossTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherImpactsOfReinsuredBusinessPreTaxIncomeTax" xlink:label="pfg_OtherImpactsOfReinsuredBusinessPreTaxIncomeTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_OtherImpactsOfReinsuredBusinessPreTaxIncomeTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeTaxFromExitedBusiness" xlink:label="pfg_IncomeTaxFromExitedBusiness" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems" xlink:to="pfg_IncomeTaxFromExitedBusiness" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureRevenuesFromContractsWithCustomersDisaggregationBySegmentDetails" xlink:type="extended" xlink:title="99942101 - Disclosure - Revenues from Contracts with Customers - Disaggregation by Segment (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="us-gaap_DisaggregationOfRevenueTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="srt_ConsolidationItemsAxis" priority="3" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512236470" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512236470" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember" xlink:label="us-gaap_OperatingSegmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:label="us-gaap_MaterialReconcilingItemsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_MaterialReconcilingItemsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="us-gaap_SubsegmentsAxis" priority="2" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372512242188" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372512242188" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInvestmentManagementMember" xlink:label="pfg_SubsegmentInvestmentManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInvestmentManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentSpecialtyBenefitsMember" xlink:label="pfg_SubsegmentSpecialtyBenefitsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentSpecialtyBenefitsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentBenefitsAndProtectionEliminationsMember" xlink:label="pfg_SubsegmentBenefitsAndProtectionEliminationsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentBenefitsAndProtectionEliminationsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentPrincipalAssetManagementEliminationsMember" xlink:label="pfg_SubsegmentPrincipalAssetManagementEliminationsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentPrincipalAssetManagementEliminationsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" priority="3" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372512253415" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372512253415" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="us-gaap_DisaggregationOfRevenueLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_DisaggregationOfRevenueTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueAbstract" xlink:label="us-gaap_DisaggregationOfRevenueAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_DisaggregationOfRevenueAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DisaggregationOfRevenueAbstract" xlink:to="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FeesAndOtherRevenuesNotWithinScopeOfRevenueRecognitionGuidance" xlink:label="pfg_FeesAndOtherRevenuesNotWithinScopeOfRevenueRecognitionGuidance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DisaggregationOfRevenueAbstract" xlink:to="pfg_FeesAndOtherRevenuesNotWithinScopeOfRevenueRecognitionGuidance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PreTaxOtherAdjustmentsInReconcilingSegmentRevenuesToConsolidatedIncome" xlink:label="pfg_PreTaxOtherAdjustmentsInReconcilingSegmentRevenuesToConsolidatedIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DisaggregationOfRevenueAbstract" xlink:to="pfg_PreTaxOtherAdjustmentsInReconcilingSegmentRevenuesToConsolidatedIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentAdvisoryAssetManagementAndInsuranceFeesAndCommissions" xlink:label="pfg_InvestmentAdvisoryAssetManagementAndInsuranceFeesAndCommissions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DisaggregationOfRevenueAbstract" xlink:to="pfg_InvestmentAdvisoryAssetManagementAndInsuranceFeesAndCommissions" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureRevenuesFromContractsWithCustomersDisaggregationWithinSegmentsDetails" xlink:type="extended" xlink:title="99942102 - Disclosure - Revenues from Contracts with Customers - Disaggregation within Segments (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="us-gaap_DisaggregationOfRevenueTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512270114" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512270114" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember" xlink:label="us-gaap_OperatingSegmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372512275802" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372512275802" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis" xlink:label="us-gaap_SubsegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="us-gaap_SubsegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain" xlink:label="us-gaap_SubsegmentsDomain_639069372512281480" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_639069372512281480" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInvestmentManagementMember" xlink:label="pfg_SubsegmentInvestmentManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInvestmentManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentInternationalPensionMember" xlink:label="pfg_SubsegmentInternationalPensionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentInternationalPensionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentSpecialtyBenefitsMember" xlink:label="pfg_SubsegmentSpecialtyBenefitsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentSpecialtyBenefitsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SubsegmentLifeInsuranceMember" xlink:label="pfg_SubsegmentLifeInsuranceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="pfg_SubsegmentLifeInsuranceMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372512287153" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372512287153" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdministrativeServiceMember" xlink:label="us-gaap_AdministrativeServiceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_AdministrativeServiceMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepositAccountMember" xlink:label="us-gaap_DepositAccountMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_DepositAccountMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ManagementServiceMember" xlink:label="us-gaap_ManagementServiceMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_ManagementServiceMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialServiceOtherMember" xlink:label="us-gaap_FinancialServiceOtherMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_FinancialServiceOtherMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CommissionIncomeMember" xlink:label="pfg_CommissionIncomeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_CommissionIncomeMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ProductsAndServicesEliminationsMember" xlink:label="pfg_ProductsAndServicesEliminationsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="srt_ProductsAndServicesDomain" xlink:to="pfg_ProductsAndServicesEliminationsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="us-gaap_DisaggregationOfRevenueLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_DisaggregationOfRevenueTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueAbstract" xlink:label="us-gaap_DisaggregationOfRevenueAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_DisaggregationOfRevenueAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DisaggregationOfRevenueAbstract" xlink:to="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_FeesAndOtherRevenuesNotWithinScopeOfRevenueRecognitionGuidance" xlink:label="pfg_FeesAndOtherRevenuesNotWithinScopeOfRevenueRecognitionGuidance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DisaggregationOfRevenueAbstract" xlink:to="pfg_FeesAndOtherRevenuesNotWithinScopeOfRevenueRecognitionGuidance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_InvestmentAdvisoryAssetManagementAndInsuranceFeesAndCommissions" xlink:label="pfg_InvestmentAdvisoryAssetManagementAndInsuranceFeesAndCommissions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DisaggregationOfRevenueAbstract" xlink:to="pfg_InvestmentAdvisoryAssetManagementAndInsuranceFeesAndCommissions" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsEarnedNet" xlink:label="us-gaap_PremiumsEarnedNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DisaggregationOfRevenueAbstract" xlink:to="us-gaap_PremiumsEarnedNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentIncome" xlink:label="us-gaap_NetInvestmentIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DisaggregationOfRevenueAbstract" xlink:to="us-gaap_NetInvestmentIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OperatingRevenues" xlink:label="pfg_OperatingRevenues" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DisaggregationOfRevenueAbstract" xlink:to="pfg_OperatingRevenues" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureStockBasedCompensationPlansStockBasedAwardsDetails" xlink:type="extended" xlink:title="99942201 - Disclosure - Stock-Based Compensation Plans - Stock-Based Awards (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis" xlink:label="us-gaap_PlanNameAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_PlanNameAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain_639069372512321269" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain_639069372512321269" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StockBasedCompensationPlansMember" xlink:label="pfg_StockBasedCompensationPlansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PlanNameDomain" xlink:to="pfg_StockBasedCompensationPlansMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StockBasedCompensationDirectorsStockPlanStockIncentivePlanAmendedAndRestatedStockIncentivePlanDirectorsStockPlanMember" xlink:label="pfg_StockBasedCompensationDirectorsStockPlanStockIncentivePlanAmendedAndRestatedStockIncentivePlanDirectorsStockPlanMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_StockBasedCompensationPlansMember" xlink:to="pfg_StockBasedCompensationDirectorsStockPlanStockIncentivePlanAmendedAndRestatedStockIncentivePlanDirectorsStockPlanMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StockBasedCompensationPlans2021StockIncentivePlanMember" xlink:label="pfg_StockBasedCompensationPlans2021StockIncentivePlanMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_StockBasedCompensationPlansMember" xlink:to="pfg_StockBasedCompensationPlans2021StockIncentivePlanMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesThatWillBeGranted" xlink:label="pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesThatWillBeGranted" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesThatWillBeGranted" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardCompensationCost1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardCompensationCost1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardCompensationCost1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ShareBasedCompensationArrangementShareBasedPaymentAwardAmountCapitalized" xlink:label="pfg_ShareBasedCompensationArrangementShareBasedPaymentAwardAmountCapitalized" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_ShareBasedCompensationArrangementShareBasedPaymentAwardAmountCapitalized" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureStockBasedCompensationPlansNonqualifiedStockOptionsActivityDetails" xlink:type="extended" xlink:title="99942202 - Disclosure - Stock-Based Compensation Plans - Nonqualified Stock Options, Activity (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639069372512338347" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639069372512338347" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="us-gaap_EmployeeStockOptionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis" xlink:label="us-gaap_PlanNameAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_PlanNameAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain_639069372512338347" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain_639069372512338347" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StockBasedCompensationPlans2014StockIncentivePlanAmendedAndRestated2010StockIncentivePlanStockIncentivePlanMember" xlink:label="pfg_StockBasedCompensationPlans2014StockIncentivePlanAmendedAndRestated2010StockIncentivePlanStockIncentivePlanMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PlanNameDomain" xlink:to="pfg_StockBasedCompensationPlans2014StockIncentivePlanAmendedAndRestated2010StockIncentivePlanStockIncentivePlanMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureStockBasedCompensationPlansNonqualifiedStockOptionsRangeOfExercisePricesDetails" xlink:type="extended" xlink:title="99942203 - Disclosure - Stock-Based Compensation Plans - Nonqualified Stock Options, Range of Exercise Prices (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639069372512366568" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639069372512366568" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="us-gaap_EmployeeStockOptionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:to="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_639069372512372210" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:to="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_639069372512372210" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ExercisePriceRange1Member" xlink:label="pfg_ExercisePriceRange1Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="pfg_ExercisePriceRange1Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ExercisePriceRange2Member" xlink:label="pfg_ExercisePriceRange2Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="pfg_ExercisePriceRange2Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ExercisePriceRange3Member" xlink:label="pfg_ExercisePriceRange3Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="pfg_ExercisePriceRange3Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ExercisePriceRange4Member" xlink:label="pfg_ExercisePriceRange4Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="pfg_ExercisePriceRange4Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ExercisePriceRange5Member" xlink:label="pfg_ExercisePriceRange5Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="pfg_ExercisePriceRange5Member" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ExercisePriceTotalRangeMember" xlink:label="pfg_ExercisePriceTotalRangeMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="pfg_ExercisePriceTotalRangeMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SummaryOfWeightedAverageRemainingContractualLivesForStockOptionsOutstandingAbstract" xlink:label="pfg_SummaryOfWeightedAverageRemainingContractualLivesForStockOptionsOutstandingAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_SummaryOfWeightedAverageRemainingContractualLivesForStockOptionsOutstandingAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_SummaryOfWeightedAverageRemainingContractualLivesForStockOptionsOutstandingAbstract" xlink:to="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_SummaryOfWeightedAverageRemainingContractualLivesForStockOptionsOutstandingAbstract" xlink:to="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_SummaryOfWeightedAverageRemainingContractualLivesForStockOptionsOutstandingAbstract" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:label="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="pfg_SummaryOfWeightedAverageRemainingContractualLivesForStockOptionsOutstandingAbstract" xlink:to="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2" xlink:label="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureStockBasedCompensationPlansNonqualifiedStockOptionsOtherDisclosuresDetails" xlink:type="extended" xlink:title="99942204 - Disclosure - Stock-Based Compensation Plans - Nonqualified Stock Options, Other Disclosures (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639069372512394788" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639069372512394788" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="us-gaap_EmployeeStockOptionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherNonqualifiedStockOptionDisclosuresAbstract" xlink:label="pfg_OtherNonqualifiedStockOptionDisclosuresAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_OtherNonqualifiedStockOptionDisclosuresAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_OtherNonqualifiedStockOptionDisclosuresAbstract" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:label="us-gaap_ProceedsFromStockOptionsExercised" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_OtherNonqualifiedStockOptionDisclosuresAbstract" xlink:to="us-gaap_ProceedsFromStockOptionsExercised" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromExerciseOfStockOptions" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromExerciseOfStockOptions" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="pfg_OtherNonqualifiedStockOptionDisclosuresAbstract" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromExerciseOfStockOptions" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureStockBasedCompensationPlansPerformanceShareAwardsAndRestrictedStockUnitsDetails" xlink:type="extended" xlink:title="99942205 - Disclosure - Stock-Based Compensation Plans - Performance Share Awards and Restricted Stock Units (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis" xlink:label="us-gaap_PlanNameAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_PlanNameAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain_639069372512406082" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain_639069372512406082" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StockBasedCompensationPlans2014StockIncentivePlanAmendedAndRestated2010StockIncentivePlanStockIncentivePlanMember" xlink:label="pfg_StockBasedCompensationPlans2014StockIncentivePlanAmendedAndRestated2010StockIncentivePlanStockIncentivePlanMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PlanNameDomain" xlink:to="pfg_StockBasedCompensationPlans2014StockIncentivePlanAmendedAndRestated2010StockIncentivePlanStockIncentivePlanMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_StockBasedCompensationPlans2021StockIncentivePlan2020DirectorsStockPlan2014DirectorsStockPlanAnd2005DirectorsStockPlanMember" xlink:label="pfg_StockBasedCompensationPlans2021StockIncentivePlan2020DirectorsStockPlan2014DirectorsStockPlanAnd2005DirectorsStockPlanMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PlanNameDomain" xlink:to="pfg_StockBasedCompensationPlans2021StockIncentivePlan2020DirectorsStockPlan2014DirectorsStockPlanAnd2005DirectorsStockPlanMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639069372512411745" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639069372512411745" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember" xlink:label="us-gaap_PerformanceSharesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_PerformanceSharesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="us-gaap_RestrictedStockUnitsRSUMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_RestrictedStockUnitsRSUMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformanceGoalsInYears" xlink:label="pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformanceGoalsInYears" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformanceGoalsInYears" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IntrinsicValueFromAwardsOrUnitsVested" xlink:label="pfg_IntrinsicValueFromAwardsOrUnitsVested" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" xlink:to="pfg_IntrinsicValueFromAwardsOrUnitsVested" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsLowerMultipleOfInitialTargetBasedOnPerformance" xlink:label="pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsLowerMultipleOfInitialTargetBasedOnPerformance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" xlink:to="pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsLowerMultipleOfInitialTargetBasedOnPerformance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsUpperLimitMultipleOfInitialTargetBasedOnPerformance" xlink:label="pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsUpperLimitMultipleOfInitialTargetBasedOnPerformance" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" xlink:to="pfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsUpperLimitMultipleOfInitialTargetBasedOnPerformance" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TaxBenefitsRealizedFromAwardsOrUnitsPaidOut" xlink:label="pfg_TaxBenefitsRealizedFromAwardsOrUnitsPaidOut" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" xlink:to="pfg_TaxBenefitsRealizedFromAwardsOrUnitsPaidOut" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureStockBasedCompensationPlansEmployeeStockPurchasePlanDetails" xlink:type="extended" xlink:title="99942206 - Disclosure - Stock-Based Compensation Plans - Employee Stock Purchase Plan (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis" xlink:label="us-gaap_PlanNameAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_PlanNameAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain_639069372512448442" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain_639069372512448442" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EmployeeStockPurchasePlanMember" xlink:label="pfg_EmployeeStockPurchasePlanMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PlanNameDomain" xlink:to="pfg_EmployeeStockPurchasePlanMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MaximumValueOfSharesAvailableForPurchasePerYear" xlink:label="pfg_MaximumValueOfSharesAvailableForPurchasePerYear" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_MaximumValueOfSharesAvailableForPurchasePerYear" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EmployeePurchasePriceAsPercentOfFairMarketValue" xlink:label="pfg_EmployeePurchasePriceAsPercentOfFairMarketValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_EmployeePurchasePriceAsPercentOfFairMarketValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EmployeeStockPurchasePlanWeightedAverageFairValueOfDiscount" xlink:label="pfg_EmployeeStockPurchasePlanWeightedAverageFairValueOfDiscount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_EmployeeStockPurchasePlanWeightedAverageFairValueOfDiscount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IntrinsicValueFromSharesSettled" xlink:label="pfg_IntrinsicValueFromSharesSettled" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_IntrinsicValueFromSharesSettled" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_CashReceivedFromSharesIssued" xlink:label="pfg_CashReceivedFromSharesIssued" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_CashReceivedFromSharesIssued" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TaxBenefitsRealizedFromSettlement" xlink:label="pfg_TaxBenefitsRealizedFromSettlement" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_TaxBenefitsRealizedFromSettlement" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EmployeeStockPurchasePlanSharesAvailableForIssuanceUnderPlan" xlink:label="pfg_EmployeeStockPurchasePlanSharesAvailableForIssuanceUnderPlan" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="pfg_EmployeeStockPurchasePlanSharesAvailableForIssuanceUnderPlan" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureEarningsPerCommonShareDetails" xlink:type="extended" xlink:title="99942301 - Disclosure - Earnings Per Common Share (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable" xlink:label="us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable" xlink:to="us-gaap_AwardTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639069372512465374" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639069372512465374" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="us-gaap_EmployeeStockOptionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="us-gaap_RestrictedStockUnitsRSUMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_RestrictedStockUnitsRSUMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember" xlink:label="us-gaap_PerformanceSharesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_PerformanceSharesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasicLineItems" xlink:label="us-gaap_EarningsPerShareBasicLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_EarningsPerShareBasicLineItems" xlink:to="us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_EarningsPerShareBasicLineItems" xlink:to="us-gaap_ProfitLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_EarningsPerShareCalculationSubtractAbstract" xlink:label="pfg_EarningsPerShareCalculationSubtractAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_EarningsPerShareBasicLineItems" xlink:to="pfg_EarningsPerShareCalculationSubtractAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:label="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_EarningsPerShareCalculationSubtractAbstract" xlink:to="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:label="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_EarningsPerShareBasicLineItems" xlink:to="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:label="us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_EarningsPerShareBasicLineItems" xlink:to="us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_EarningsPerShareBasicLineItems" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:to="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:label="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract" xlink:to="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:to="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_NetIncomeLossPerCommonShareAbstract" xlink:label="pfg_NetIncomeLossPerCommonShareAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_EarningsPerShareBasicLineItems" xlink:to="pfg_NetIncomeLossPerCommonShareAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic" xlink:label="us-gaap_EarningsPerShareBasic" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_NetIncomeLossPerCommonShareAbstract" xlink:to="us-gaap_EarningsPerShareBasic" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="us-gaap_EarningsPerShareDiluted" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="pfg_NetIncomeLossPerCommonShareAbstract" xlink:to="us-gaap_EarningsPerShareDiluted" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureSubsequentEventDetails" xlink:type="extended" xlink:title="99942401 - Disclosure - Subsequent Event (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTable" xlink:label="us-gaap_SubsequentEventTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="us-gaap_SubsequentEventTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_SubsequentEventTable" xlink:to="us-gaap_SubsequentEventTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain_639069372512510441" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain_639069372512510441" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember" xlink:label="us-gaap_SubsequentEventMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsequentEventTypeDomain" xlink:to="us-gaap_SubsequentEventMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_SubsequentEventTable" xlink:to="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:to="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_639069372512510441" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:to="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_639069372512510441" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PrincipalCompaniaDeSegurosDeVidaChileS.a.Member" xlink:label="pfg_PrincipalCompaniaDeSegurosDeVidaChileS.a.Member" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:to="pfg_PrincipalCompaniaDeSegurosDeVidaChileS.a.Member" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis" xlink:label="us-gaap_DisposalGroupClassificationAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_SubsequentEventTable" xlink:to="us-gaap_DisposalGroupClassificationAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain" xlink:label="us-gaap_DisposalGroupClassificationDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DisposalGroupClassificationAxis" xlink:to="us-gaap_DisposalGroupClassificationDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain" xlink:label="us-gaap_DisposalGroupClassificationDomain_639069372512516049" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DisposalGroupClassificationAxis" xlink:to="us-gaap_DisposalGroupClassificationDomain_639069372512516049" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember" xlink:label="us-gaap_DiscontinuedOperationsDisposedOfBySaleMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DisposalGroupClassificationDomain" xlink:to="us-gaap_DiscontinuedOperationsDisposedOfBySaleMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementScenarioAxis" xlink:label="srt_StatementScenarioAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_SubsequentEventTable" xlink:to="srt_StatementScenarioAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="srt_ScenarioUnspecifiedDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_StatementScenarioAxis" xlink:to="srt_ScenarioUnspecifiedDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="srt_ScenarioUnspecifiedDomain_639069372512521625" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_StatementScenarioAxis" xlink:to="srt_ScenarioUnspecifiedDomain_639069372512521625" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioForecastMember" xlink:label="srt_ScenarioForecastMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ScenarioUnspecifiedDomain" xlink:to="srt_ScenarioForecastMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventLineItems" xlink:label="us-gaap_SubsequentEventLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="us-gaap_SubsequentEventTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" xlink:label="us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposalStatementOfIncomeExtensibleList" xlink:label="us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposalStatementOfIncomeExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" xlink:to="us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposalStatementOfIncomeExtensibleList" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureScheduleISummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesDetails" xlink:type="extended" xlink:title="99942501 - Disclosure - Schedule I - Summary of Investments - Other Than Investments in Related Parties (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesTable" xlink:label="srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeAxis" xlink:label="us-gaap_InvestmentTypeAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesTable" xlink:to="us-gaap_InvestmentTypeAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="us-gaap_InvestmentTypeCategorizationMember_639069372512532925" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_InvestmentTypeAxis" xlink:to="us-gaap_InvestmentTypeCategorizationMember_639069372512532925" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesMember" xlink:label="us-gaap_DebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_DebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasuryAndGovernmentMember" xlink:label="us-gaap_USTreasuryAndGovernmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_USTreasuryAndGovernmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember" xlink:label="us-gaap_USStatesAndPoliticalSubdivisionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_USStatesAndPoliticalSubdivisionsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignGovernmentDebtSecuritiesMember" xlink:label="us-gaap_ForeignGovernmentDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_ForeignGovernmentDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PublicUtilityBondsMember" xlink:label="us-gaap_PublicUtilityBondsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_PublicUtilityBondsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RedeemablePreferredStockMember" xlink:label="us-gaap_RedeemablePreferredStockMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_RedeemablePreferredStockMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllOtherCorporateBondsMember" xlink:label="us-gaap_AllOtherCorporateBondsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_AllOtherCorporateBondsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember" xlink:label="us-gaap_ResidentialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_ResidentialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember" xlink:label="us-gaap_CommercialMortgageBackedSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CommercialMortgageBackedSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralizedDebtObligationsMember" xlink:label="us-gaap_CollateralizedDebtObligationsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_CollateralizedDebtObligationsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherDebtSecuritiesMember" xlink:label="us-gaap_OtherDebtSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_DebtSecuritiesMember" xlink:to="us-gaap_OtherDebtSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedMaturitiesMember" xlink:label="us-gaap_FixedMaturitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_FixedMaturitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesMember" xlink:label="us-gaap_EquitySecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_EquitySecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BanksTrustAndInsuranceEquitiesMember" xlink:label="us-gaap_BanksTrustAndInsuranceEquitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_EquitySecuritiesMember" xlink:to="us-gaap_BanksTrustAndInsuranceEquitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PublicUtilityEquitiesMember" xlink:label="us-gaap_PublicUtilityEquitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_EquitySecuritiesMember" xlink:to="us-gaap_PublicUtilityEquitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndustrialMiscellaneousAndAllOthersMember" xlink:label="us-gaap_IndustrialMiscellaneousAndAllOthersMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_EquitySecuritiesMember" xlink:to="us-gaap_IndustrialMiscellaneousAndAllOthersMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherCorporateEquitiesMember" xlink:label="pfg_OtherCorporateEquitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_EquitySecuritiesMember" xlink:to="pfg_OtherCorporateEquitiesMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonredeemablePreferredStockMember" xlink:label="us-gaap_NonredeemablePreferredStockMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_EquitySecuritiesMember" xlink:to="us-gaap_NonredeemablePreferredStockMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_MortgageLoansMember" xlink:label="pfg_MortgageLoansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="pfg_MortgageLoansMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RealEstateAcquiredInSatisfactionOfDebtMember" xlink:label="us-gaap_RealEstateAcquiredInSatisfactionOfDebtMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_RealEstateAcquiredInSatisfactionOfDebtMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RealEstateInvestmentMember" xlink:label="us-gaap_RealEstateInvestmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_RealEstateInvestmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyLoansMember" xlink:label="us-gaap_PolicyLoansMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_PolicyLoansMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLongTermInvestmentsMember" xlink:label="us-gaap_OtherLongTermInvestmentsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_InvestmentTypeCategorizationMember" xlink:to="us-gaap_OtherLongTermInvestmentsMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="us-gaap_FinancialInstrumentAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesTable" xlink:to="us-gaap_FinancialInstrumentAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372512567016" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_639069372512567016" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_AvailableForSaleSecurityMember" xlink:label="pfg_AvailableForSaleSecurityMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_AvailableForSaleSecurityMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_TradingSecuritiesMember" xlink:label="pfg_TradingSecuritiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="pfg_TradingSecuritiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesReportableDataLineItems" xlink:label="srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesReportableDataLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesReportableDataLineItems" xlink:to="srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost" xlink:label="us-gaap_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesReportableDataLineItems" xlink:to="us-gaap_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue" xlink:label="us-gaap_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesReportableDataLineItems" xlink:to="us-gaap_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount" xlink:label="us-gaap_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesReportableDataLineItems" xlink:to="us-gaap_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesUnallocatedPortfolioLayerMethodBasisAdjustmentCost" xlink:label="pfg_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesUnallocatedPortfolioLayerMethodBasisAdjustmentCost" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesReportableDataLineItems" xlink:to="pfg_SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesUnallocatedPortfolioLayerMethodBasisAdjustmentCost" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfFinancialPositionDetails" xlink:type="extended" xlink:title="99942601 - Disclosure - Schedule II - Condensed Financial Information of Registrant (Parent Only) - Statements of Financial Position (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScheduleOfCondensedFinancialStatementsTable" xlink:label="srt_ScheduleOfCondensedFinancialStatementsTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis" xlink:label="srt_ConsolidatedEntitiesAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTable" xlink:to="srt_ConsolidatedEntitiesAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain_639069372512584604" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain_639069372512584604" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ParentCompanyMember" xlink:label="srt_ParentCompanyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidatedEntitiesDomain" xlink:to="srt_ParentCompanyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512584604" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512584604" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ReportableLegalEntitiesMember" xlink:label="srt_ReportableLegalEntitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="srt_ReportableLegalEntitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CondensedFinancialStatementsCaptionsLineItems" xlink:label="srt_CondensedFinancialStatementsCaptionsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="srt_ScheduleOfCondensedFinancialStatementsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract" xlink:label="us-gaap_AssetsAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_AssetsAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" xlink:label="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradingSecuritiesDebt" xlink:label="us-gaap_TradingSecuritiesDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_TradingSecuritiesDebt" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherInvestments" xlink:label="us-gaap_OtherInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_OtherInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReceivable" xlink:label="us-gaap_IncomeTaxReceivable" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_IncomeTaxReceivable" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxAssetsNet" xlink:label="us-gaap_DeferredIncomeTaxAssetsNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_DeferredIncomeTaxAssetsNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherReceivables" xlink:label="us-gaap_OtherReceivables" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_OtherReceivables" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherAssetsAsDefined" xlink:label="pfg_OtherAssetsAsDefined" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_AssetsAbstract" xlink:to="pfg_OtherAssetsAsDefined" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityMethodInvestments" xlink:label="us-gaap_EquityMethodInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_EquityMethodInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_Assets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAbstract" xlink:label="us-gaap_LiabilitiesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_LiabilitiesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt" xlink:label="us-gaap_LongTermDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_LiabilitiesAbstract" xlink:to="us-gaap_LongTermDebt" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestPayableCurrentAndNoncurrent" xlink:label="us-gaap_InterestPayableCurrentAndNoncurrent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LiabilitiesAbstract" xlink:to="us-gaap_InterestPayableCurrentAndNoncurrent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPensionPlanCurrentAndNoncurrentLiabilities" xlink:label="us-gaap_DefinedBenefitPensionPlanCurrentAndNoncurrentLiabilities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LiabilitiesAbstract" xlink:to="us-gaap_DefinedBenefitPensionPlanCurrentAndNoncurrentLiabilities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OtherLiabilitiesAsDefined" xlink:label="pfg_OtherLiabilitiesAsDefined" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LiabilitiesAbstract" xlink:to="pfg_OtherLiabilitiesAsDefined" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities" xlink:label="us-gaap_Liabilities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_LiabilitiesAbstract" xlink:to="us-gaap_Liabilities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockValue" xlink:label="us-gaap_CommonStockValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_CommonStockValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="us-gaap_AdditionalPaidInCapital" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_AdditionalPaidInCapital" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonValue" xlink:label="us-gaap_TreasuryStockCommonValue" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_TreasuryStockCommonValue" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_StockholdersEquity" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfFinancialPositionParentheticalDetails" xlink:type="extended" xlink:title="99942602 - Disclosure - Schedule II - Condensed Financial Information of Registrant (Parent Only) - Statements of Financial Position - Parenthetical (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScheduleOfCondensedFinancialStatementsTable" xlink:label="srt_ScheduleOfCondensedFinancialStatementsTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis" xlink:label="srt_ConsolidatedEntitiesAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTable" xlink:to="srt_ConsolidatedEntitiesAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain_639069372512630223" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain_639069372512630223" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ParentCompanyMember" xlink:label="srt_ParentCompanyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidatedEntitiesDomain" xlink:to="srt_ParentCompanyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512635975" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512635975" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ReportableLegalEntitiesMember" xlink:label="srt_ReportableLegalEntitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="srt_ReportableLegalEntitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CondensedFinancialStatementsCaptionsLineItems" xlink:label="srt_CondensedFinancialStatementsCaptionsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="srt_ScheduleOfCondensedFinancialStatementsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="us-gaap_CommonStockSharesAuthorized" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_CommonStockSharesAuthorized" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesIssued" xlink:label="us-gaap_CommonStockSharesIssued" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_CommonStockSharesIssued" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="us-gaap_CommonStockSharesOutstanding" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_CommonStockSharesOutstanding" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonShares" xlink:label="us-gaap_TreasuryStockCommonShares" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_TreasuryStockCommonShares" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfOperationsDetails" xlink:type="extended" xlink:title="99942603 - Disclosure - Schedule II - Condensed Financial Information of Registrant (Parent Only) - Statements of Operations (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScheduleOfCondensedFinancialStatementsTable" xlink:label="srt_ScheduleOfCondensedFinancialStatementsTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis" xlink:label="srt_ConsolidatedEntitiesAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTable" xlink:to="srt_ConsolidatedEntitiesAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain_639069372512647371" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain_639069372512647371" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ParentCompanyMember" xlink:label="srt_ParentCompanyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidatedEntitiesDomain" xlink:to="srt_ParentCompanyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512653088" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512653088" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ReportableLegalEntitiesMember" xlink:label="srt_ReportableLegalEntitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="srt_ReportableLegalEntitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CondensedFinancialStatementsCaptionsLineItems" xlink:label="srt_CondensedFinancialStatementsCaptionsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="srt_ScheduleOfCondensedFinancialStatementsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenuesAbstract" xlink:label="us-gaap_RevenuesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_RevenuesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentIncome" xlink:label="us-gaap_NetInvestmentIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_RevenuesAbstract" xlink:to="us-gaap_NetInvestmentIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnInvestments" xlink:label="us-gaap_GainLossOnInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_RevenuesAbstract" xlink:to="us-gaap_GainLossOnInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues" xlink:label="us-gaap_Revenues" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_RevenuesAbstract" xlink:to="us-gaap_Revenues" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BenefitsLossesAndExpensesAbstract" xlink:label="us-gaap_BenefitsLossesAndExpensesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_BenefitsLossesAndExpensesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" xlink:label="pfg_OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_BenefitsLossesAndExpensesAbstract" xlink:to="pfg_OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BenefitsLossesAndExpenses" xlink:label="us-gaap_BenefitsLossesAndExpenses" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_BenefitsLossesAndExpensesAbstract" xlink:to="us-gaap_BenefitsLossesAndExpenses" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_IncomeLossFromContinuingOperationsBeforeIncomeTaxes" xlink:label="pfg_IncomeLossFromContinuingOperationsBeforeIncomeTaxes" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="pfg_IncomeLossFromContinuingOperationsBeforeIncomeTaxes" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_IncomeTaxExpenseBenefit" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_IncomeLossFromEquityMethodInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_NetIncomeLoss" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyStatementsOfCashFlowsDetails" xlink:type="extended" xlink:title="99942604 - Disclosure - Schedule II - Condensed Financial Information of Registrant (Parent Only) - Statements of Cash Flows (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScheduleOfCondensedFinancialStatementsTable" xlink:label="srt_ScheduleOfCondensedFinancialStatementsTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis" xlink:label="srt_ConsolidatedEntitiesAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTable" xlink:to="srt_ConsolidatedEntitiesAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain_639069372512675902" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain_639069372512675902" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ParentCompanyMember" xlink:label="srt_ParentCompanyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidatedEntitiesDomain" xlink:to="srt_ParentCompanyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512675902" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512675902" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ReportableLegalEntitiesMember" xlink:label="srt_ReportableLegalEntitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="srt_ReportableLegalEntitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CondensedFinancialStatementsCaptionsLineItems" xlink:label="srt_CondensedFinancialStatementsCaptionsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="srt_ScheduleOfCondensedFinancialStatementsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_ProfitLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnInvestments" xlink:label="us-gaap_GainLossOnInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_GainLossOnInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation" xlink:label="us-gaap_ShareBasedCompensation" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_ShareBasedCompensation" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_IncomeLossFromEquityMethodInvestments" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ProceedsFromPaymentsForTradingSecuritiesAndEquitySecuritiesWithOperatingIntent" xlink:label="pfg_ProceedsFromPaymentsForTradingSecuritiesAndEquitySecuritiesWithOperatingIntent" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="pfg_ProceedsFromPaymentsForTradingSecuritiesAndEquitySecuritiesWithOperatingIntent" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInIncomeTaxes" xlink:label="us-gaap_IncreaseDecreaseInIncomeTaxes" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInIncomeTaxes" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement" xlink:label="us-gaap_OtherOperatingActivitiesCashFlowStatement" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_OtherOperatingActivitiesCashFlowStatement" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireMarketableSecurities" xlink:label="us-gaap_PaymentsToAcquireMarketableSecurities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_PaymentsToAcquireMarketableSecurities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ProceedsFromMaturitiesRepaymentsAndCallsOfDebtSecuritiesAvailableForSaleAndEquitySecuritiesFvNi" xlink:label="pfg_ProceedsFromMaturitiesRepaymentsAndCallsOfDebtSecuritiesAvailableForSaleAndEquitySecuritiesFvNi" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="pfg_ProceedsFromMaturitiesRepaymentsAndCallsOfDebtSecuritiesAvailableForSaleAndEquitySecuritiesFvNi" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForProceedsFromProductiveAssets" xlink:label="us-gaap_PaymentsForProceedsFromProductiveAssets" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_PaymentsForProceedsFromProductiveAssets" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xlink:label="us-gaap_PaymentsForProceedsFromOtherInvestingActivities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_PaymentsForProceedsFromOtherInvestingActivities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DividendsReceivedFromContributionsToUnconsolidatedEntities" xlink:label="pfg_DividendsReceivedFromContributionsToUnconsolidatedEntities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="pfg_DividendsReceivedFromContributionsToUnconsolidatedEntities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="us-gaap_PaymentsForRepurchaseOfCommonStock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_PaymentsForRepurchaseOfCommonStock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDividendsCommonStock" xlink:label="us-gaap_PaymentsOfDividendsCommonStock" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_PaymentsOfDividendsCommonStock" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="us-gaap_RepaymentsOfLongTermDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_RepaymentsOfLongTermDebt" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:label="us-gaap_ProceedsFromIssuanceOfLongTermDebt" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromIssuanceOfLongTermDebt" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivities" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureScheduleIiCondensedFinancialInformationOfRegistrantParentOnlyFinancialStatementFootnotesDetails" xlink:type="extended" xlink:title="99942605 - Disclosure - Schedule II - Condensed Financial Information of Registrant (Parent Only) - Financial Statement Footnotes (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScheduleOfCondensedFinancialStatementsTable" xlink:label="srt_ScheduleOfCondensedFinancialStatementsTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis" xlink:label="srt_ConsolidatedEntitiesAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTable" xlink:to="srt_ConsolidatedEntitiesAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain" xlink:label="srt_ConsolidatedEntitiesDomain_639069372512727804" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidatedEntitiesAxis" xlink:to="srt_ConsolidatedEntitiesDomain_639069372512727804" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ParentCompanyMember" xlink:label="srt_ParentCompanyMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidatedEntitiesDomain" xlink:to="srt_ParentCompanyMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTable" xlink:to="srt_ConsolidationItemsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_639069372512727804" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_639069372512727804" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ReportableLegalEntitiesMember" xlink:label="srt_ReportableLegalEntitiesMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ConsolidationItemsDomain" xlink:to="srt_ReportableLegalEntitiesMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CondensedFinancialStatementsCaptionsLineItems" xlink:label="srt_CondensedFinancialStatementsCaptionsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="srt_ScheduleOfCondensedFinancialStatementsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PlanAssetsHeldInRabbiTrusts" xlink:label="pfg_PlanAssetsHeldInRabbiTrusts" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="pfg_PlanAssetsHeldInRabbiTrusts" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_PlanLiabilitiesHeldInRabbiTrusts" xlink:label="pfg_PlanLiabilitiesHeldInRabbiTrusts" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="pfg_PlanLiabilitiesHeldInRabbiTrusts" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanTaxStatusExtensibleList" xlink:label="us-gaap_DefinedBenefitPlanTaxStatusExtensibleList" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="us-gaap_DefinedBenefitPlanTaxStatusExtensibleList" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DividendsReceivedFromContributionsToUnconsolidatedEntitiesAbstract" xlink:label="pfg_DividendsReceivedFromContributionsToUnconsolidatedEntitiesAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_CondensedFinancialStatementsCaptionsLineItems" xlink:to="pfg_DividendsReceivedFromContributionsToUnconsolidatedEntitiesAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_DividendsReceivedFromContributionsToUnconsolidatedEntities" xlink:label="pfg_DividendsReceivedFromContributionsToUnconsolidatedEntities" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="pfg_DividendsReceivedFromContributionsToUnconsolidatedEntitiesAbstract" xlink:to="pfg_DividendsReceivedFromContributionsToUnconsolidatedEntities" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureScheduleIiiSupplementaryInsuranceInformationDetails" xlink:type="extended" xlink:title="99942701 - Disclosure - Schedule III - Supplementary Insurance Information (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SupplementaryInsuranceInformationBySegmentTable" xlink:label="srt_SupplementaryInsuranceInformationBySegmentTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="srt_SupplementaryInsuranceInformationBySegmentTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639069372512738627" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_639069372512738627" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentRetirementAndIncomeSolutionsMember" xlink:label="pfg_SegmentRetirementAndIncomeSolutionsMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentRetirementAndIncomeSolutionsMember" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentCorporateMember" xlink:label="pfg_SegmentCorporateMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentCorporateMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentBenefitsAndProtectionMember" xlink:label="pfg_SegmentBenefitsAndProtectionMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentBenefitsAndProtectionMember" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_SegmentPrincipalAssetManagementMember" xlink:label="pfg_SegmentPrincipalAssetManagementMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_SegmentDomain" xlink:to="pfg_SegmentPrincipalAssetManagementMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:label="srt_SupplementaryInsuranceInformationBySegmentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="srt_SupplementaryInsuranceInformationBySegmentTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCosts" xlink:label="us-gaap_DeferredPolicyAcquisitionCosts" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCosts" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitAssetAmount" xlink:label="us-gaap_MarketRiskBenefitAssetAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="us-gaap_MarketRiskBenefitAssetAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitsAndUnpaidClaimsAndClaimsAdjustmentExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="pfg-20251231.xsd#pfg_ContractholderAndOtherPolicyholderFunds" xlink:label="pfg_ContractholderAndOtherPolicyholderFunds" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="pfg_ContractholderAndOtherPolicyholderFunds" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitLiabilityAmount" xlink:label="us-gaap_MarketRiskBenefitLiabilityAmount" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="us-gaap_MarketRiskBenefitLiabilityAmount" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsEarnedNet" xlink:label="us-gaap_PremiumsEarnedNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="us-gaap_PremiumsEarnedNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentIncome" xlink:label="us-gaap_NetInvestmentIncome" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="us-gaap_NetInvestmentIncome" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" xlink:label="us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="us-gaap_PolicyholderBenefitsAndClaimsIncurredNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitRemeasurementGainLoss" xlink:label="us-gaap_LiabilityForFuturePolicyBenefitRemeasurementGainLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="us-gaap_LiabilityForFuturePolicyBenefitRemeasurementGainLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketRiskBenefitChangeInFairValueGainLoss" xlink:label="us-gaap_MarketRiskBenefitChangeInFairValueGainLoss" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="us-gaap_MarketRiskBenefitChangeInFairValueGainLoss" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" xlink:label="us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplementaryInsuranceInformationOtherOperatingExpense" xlink:label="us-gaap_SupplementaryInsuranceInformationOtherOperatingExpense" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="srt_SupplementaryInsuranceInformationBySegmentLineItems" xlink:to="us-gaap_SupplementaryInsuranceInformationOtherOperatingExpense" priority="1" use="optional" />
  </definitionLink>
  <definitionLink xlink:role="http://principal.com/role/DisclosureScheduleIvReinsuranceDetails" xlink:type="extended" xlink:title="99942801 - Disclosure - Schedule IV - Reinsurance (Details)" xmlns="http://www.xbrl.org/2003/linkbase">
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable" xlink:label="srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable" xlink:to="srt_ProductOrServiceAxis" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639069372512787566" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_639069372512787566" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LifeAndAnnuityInsuranceProductLineMember" xlink:label="us-gaap_LifeAndAnnuityInsuranceProductLineMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_LifeAndAnnuityInsuranceProductLineMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccidentAndHealthInsuranceSegmentMember" xlink:label="us-gaap_AccidentAndHealthInsuranceSegmentMember" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ProductsAndServicesDomain" xlink:to="us-gaap_AccidentAndHealthInsuranceSegmentMember" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems" xlink:label="srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems" xlink:to="srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LifeInsuranceInForceNetAbstract" xlink:label="srt_LifeInsuranceInForceNetAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems" xlink:to="srt_LifeInsuranceInForceNetAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LifeInsuranceInForceGross" xlink:label="srt_LifeInsuranceInForceGross" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_LifeInsuranceInForceNetAbstract" xlink:to="srt_LifeInsuranceInForceGross" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LifeInsuranceInForceCeded" xlink:label="srt_LifeInsuranceInForceCeded" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_LifeInsuranceInForceNetAbstract" xlink:to="srt_LifeInsuranceInForceCeded" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LifeInsuranceInForceAssumed" xlink:label="srt_LifeInsuranceInForceAssumed" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_LifeInsuranceInForceNetAbstract" xlink:to="srt_LifeInsuranceInForceAssumed" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LifeInsuranceInForceNet" xlink:label="srt_LifeInsuranceInForceNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_LifeInsuranceInForceNetAbstract" xlink:to="srt_LifeInsuranceInForceNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LifeInsuranceInForcePercentageAssumedToNet" xlink:label="srt_LifeInsuranceInForcePercentageAssumedToNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_LifeInsuranceInForceNetAbstract" xlink:to="srt_LifeInsuranceInForcePercentageAssumedToNet" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentNetAmountAbstract" xlink:label="us-gaap_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentNetAmountAbstract" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems" xlink:to="us-gaap_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentNetAmountAbstract" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectPremiumsEarned" xlink:label="us-gaap_DirectPremiumsEarned" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentNetAmountAbstract" xlink:to="us-gaap_DirectPremiumsEarned" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededPremiumsEarned" xlink:label="us-gaap_CededPremiumsEarned" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentNetAmountAbstract" xlink:to="us-gaap_CededPremiumsEarned" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssumedPremiumsEarned" xlink:label="us-gaap_AssumedPremiumsEarned" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentNetAmountAbstract" xlink:to="us-gaap_AssumedPremiumsEarned" priority="1" use="optional" />
    <loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsEarnedNet" xlink:label="us-gaap_PremiumsEarnedNet" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentNetAmountAbstract" xlink:to="us-gaap_PremiumsEarnedNet" priority="1" use="optional" />
  </definitionLink>
</link:linkbase>
