<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:3446719c-5c3d-4dbc-a53e-bb751c0ebca2,g:813fbd15-7274-4ff7-a8f4-dc46449363f8-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <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/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: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:roleRef roleURI="http://bayfirstfinancial.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="simple" xlink:href="bafn-20251231.xsd#CONSOLIDATEDBALANCESHEETS"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_69d082f1-59e1-49ea-b783-042c2fbd998d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_9176ad0e-22a5-4e0a-a9cb-372cd4134fca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_69d082f1-59e1-49ea-b783-042c2fbd998d" xlink:to="loc_us-gaap_StatementTable_9176ad0e-22a5-4e0a-a9cb-372cd4134fca" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_43c1b38c-4607-452a-9dcf-e16495b808e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_9176ad0e-22a5-4e0a-a9cb-372cd4134fca" xlink:to="loc_us-gaap_StatementClassOfStockAxis_43c1b38c-4607-452a-9dcf-e16495b808e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_43c1b38c-4607-452a-9dcf-e16495b808e3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_43c1b38c-4607-452a-9dcf-e16495b808e3" xlink:to="loc_us-gaap_ClassOfStockDomain_43c1b38c-4607-452a-9dcf-e16495b808e3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_aad61e2a-d09f-4512-ab29-5d59a186e6e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_43c1b38c-4607-452a-9dcf-e16495b808e3" xlink:to="loc_us-gaap_ClassOfStockDomain_aad61e2a-d09f-4512-ab29-5d59a186e6e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_7b0079cf-7916-4ab1-bf3b-df64bd842442" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_aad61e2a-d09f-4512-ab29-5d59a186e6e4" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_7b0079cf-7916-4ab1-bf3b-df64bd842442" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesBPreferredStockMember_1e02909d-c188-40bc-8fcd-8358703a89ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesBPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_aad61e2a-d09f-4512-ab29-5d59a186e6e4" xlink:to="loc_us-gaap_SeriesBPreferredStockMember_1e02909d-c188-40bc-8fcd-8358703a89ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesCPreferredStockMember_2d1c1e73-5d91-40f9-afb8-6af7cafc1550" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesCPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_aad61e2a-d09f-4512-ab29-5d59a186e6e4" xlink:to="loc_us-gaap_SeriesCPreferredStockMember_2d1c1e73-5d91-40f9-afb8-6af7cafc1550" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_69d082f1-59e1-49ea-b783-042c2fbd998d" xlink:to="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndDueFromBanks_a28a0e6e-7d56-4569-92e4-25f8c1980fb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndDueFromBanks"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_CashAndDueFromBanks_a28a0e6e-7d56-4569-92e4-25f8c1980fb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestBearingDepositsInBanks_4596b2cd-e4ab-4bc6-b959-edd0868fbbe8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestBearingDepositsInBanks"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_InterestBearingDepositsInBanks_4596b2cd-e4ab-4bc6-b959-edd0868fbbe8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_2f702c11-8e87-4102-be7c-ac8c6128e3c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_2f702c11-8e87-4102-be7c-ac8c6128e3c8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_TimeDepositsNotClassifiedAsCashAndCashEquivalents_0bbbae3b-8bb8-406d-a6e8-13707436ca77" xlink:href="bafn-20251231.xsd#bafn_TimeDepositsNotClassifiedAsCashAndCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_bafn_TimeDepositsNotClassifiedAsCashAndCashEquivalents_0bbbae3b-8bb8-406d-a6e8-13707436ca77" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_e68ecaf0-741f-4512-934f-3d312be89774" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_e68ecaf0-741f-4512-934f-3d312be89774" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_4623b22d-fc19-498d-84d9-0527f519b483" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_4623b22d-fc19-498d-84d9-0527f519b483" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_NonmarketableEquitySecurities_0ef94d4c-1c9d-41c0-8687-cbb88fa334b2" xlink:href="bafn-20251231.xsd#bafn_NonmarketableEquitySecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_bafn_NonmarketableEquitySecurities_0ef94d4c-1c9d-41c0-8687-cbb88fa334b2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableFairValueDisclosure_6fff44a7-c041-4576-8c90-46c66141fc92" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LoansReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_LoansReceivableFairValueDisclosure_6fff44a7-c041-4576-8c90-46c66141fc92" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_8721f883-f3fa-417b-bdc0-20ca3060dadb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_8721f883-f3fa-417b-bdc0-20ca3060dadb" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_6dc4e2f4-d54e-48b8-bcd4-dec46f73a6c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_6dc4e2f4-d54e-48b8-bcd4-dec46f73a6c8" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_c46f00f6-bd4f-4218-92b3-7128012bba40" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_c46f00f6-bd4f-4218-92b3-7128012bba40" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAccruedInterestBeforeAllowanceForCreditLoss_531a0c7d-4819-4f42-a07b-7b5ada2da706" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_FinancingReceivableAccruedInterestBeforeAllowanceForCreditLoss_531a0c7d-4819-4f42-a07b-7b5ada2da706" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_PropertyPlantAndEquipmentNetContinuingOperations_a6959b7f-7d7f-48c7-8635-ffe36a65ac00" xlink:href="bafn-20251231.xsd#bafn_PropertyPlantAndEquipmentNetContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_bafn_PropertyPlantAndEquipmentNetContinuingOperations_a6959b7f-7d7f-48c7-8635-ffe36a65ac00" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtAmortizedValue_f7282afa-12b9-47e8-b183-597a5021fe95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetAtAmortizedValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_ServicingAssetAtAmortizedValue_f7282afa-12b9-47e8-b183-597a5021fe95" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_e18c4b3c-9bbd-4b68-8b4e-4c3473fa37d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_e18c4b3c-9bbd-4b68-8b4e-4c3473fa37d7" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_cca8873b-d374-49e7-91ec-69e0b3404517" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_cca8873b-d374-49e7-91ec-69e0b3404517" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BankOwnedLifeInsurance_97bd76ec-6713-4461-8f07-1120e44b607d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BankOwnedLifeInsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_BankOwnedLifeInsurance_97bd76ec-6713-4461-8f07-1120e44b607d" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRealEstate_9a2b227c-9f6c-4d16-ad38-4128d1151354" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherRealEstate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_OtherRealEstate_9a2b227c-9f6c-4d16-ad38-4128d1151354" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_026cffe4-ad26-4d76-bcdf-6d06eed56ecd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_OtherAssets_026cffe4-ad26-4d76-bcdf-6d06eed56ecd" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_1af764e3-b02b-4da4-be61-c26d5f3bedf2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_cf34f0d7-afd7-4d60-a328-6c1479f74471" xlink:to="loc_us-gaap_Assets_1af764e3-b02b-4da4-be61-c26d5f3bedf2" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04f0ed13-6b02-4d80-b549-eaf7ced186cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_69d082f1-59e1-49ea-b783-042c2fbd998d" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04f0ed13-6b02-4d80-b549-eaf7ced186cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04f0ed13-6b02-4d80-b549-eaf7ced186cf" xlink:to="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestBearingDepositLiabilities_415b5f38-8825-49a9-b3b4-bef4e5bbf70a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoninterestBearingDepositLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_us-gaap_NoninterestBearingDepositLiabilities_415b5f38-8825-49a9-b3b4-bef4e5bbf70a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestBearingDepositLiabilities_9f1ceaf4-bd13-4bc8-8e9f-9b38c565aeea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestBearingDepositLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_us-gaap_InterestBearingDepositLiabilities_9f1ceaf4-bd13-4bc8-8e9f-9b38c565aeea" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_DepositsSavingsAndMoneyMarketDeposits_aee84a10-2faa-4e7e-be4c-133883e70020" xlink:href="bafn-20251231.xsd#bafn_DepositsSavingsAndMoneyMarketDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_bafn_DepositsSavingsAndMoneyMarketDeposits_aee84a10-2faa-4e7e-be4c-133883e70020" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimeDeposits_50525a0b-3e62-4c5b-9124-c401743f48a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TimeDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_us-gaap_TimeDeposits_50525a0b-3e62-4c5b-9124-c401743f48a0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Deposits_433bf591-591a-41b1-a1eb-acd2ee315b38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Deposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_us-gaap_Deposits_433bf591-591a-41b1-a1eb-acd2ee315b38" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedDebt_2d977dc6-8903-4de7-82b9-cb8f4a697586" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubordinatedDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_us-gaap_SubordinatedDebt_2d977dc6-8903-4de7-82b9-cb8f4a697586" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayable_20a61dd0-a1ec-427a-b534-0d7d218f9451" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NotesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_us-gaap_NotesPayable_20a61dd0-a1ec-427a-b534-0d7d218f9451" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrentAndNoncurrent_e4a72eb9-50da-43e7-86d2-92fc974ea116" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_us-gaap_InterestPayableCurrentAndNoncurrent_e4a72eb9-50da-43e7-86d2-92fc974ea116" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_OperatingLeaseLiabilityContinuingOperations_6233d126-c291-4c87-ba24-f4b235737cd5" xlink:href="bafn-20251231.xsd#bafn_OperatingLeaseLiabilityContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_bafn_OperatingLeaseLiabilityContinuingOperations_6233d126-c291-4c87-ba24-f4b235737cd5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_bd1460e8-6228-47f9-999e-4c43db260ffa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_bd1460e8-6228-47f9-999e-4c43db260ffa" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_740b0a28-ad29-4dd2-b00d-b8d38629f8d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_740b0a28-ad29-4dd2-b00d-b8d38629f8d1" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_768aec8f-ea03-45e9-9209-42e1d0b36dbd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_bb2b7633-8131-400e-bee5-0b98cf0031cb" xlink:to="loc_us-gaap_Liabilities_768aec8f-ea03-45e9-9209-42e1d0b36dbd" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_4dae5a28-d4e8-487c-86a4-8038b9dbcb5e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04f0ed13-6b02-4d80-b549-eaf7ced186cf" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_4dae5a28-d4e8-487c-86a4-8038b9dbcb5e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_a3ecf755-2449-4a17-902a-2e6202ee97b0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_4dae5a28-d4e8-487c-86a4-8038b9dbcb5e" xlink:to="loc_us-gaap_PreferredStockValue_a3ecf755-2449-4a17-902a-2e6202ee97b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStocksIncludingAdditionalPaidInCapital_7f582e95-f81d-4e0a-b7f6-e7e7d52464ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStocksIncludingAdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_4dae5a28-d4e8-487c-86a4-8038b9dbcb5e" xlink:to="loc_us-gaap_CommonStocksIncludingAdditionalPaidInCapital_7f582e95-f81d-4e0a-b7f6-e7e7d52464ab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_5561a01b-1e26-46b6-84c8-93a600c9d3cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_4dae5a28-d4e8-487c-86a4-8038b9dbcb5e" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_5561a01b-1e26-46b6-84c8-93a600c9d3cd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationEquity_4116be1b-4cfa-4e8e-b1b2-999de0f44e3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_4dae5a28-d4e8-487c-86a4-8038b9dbcb5e" xlink:to="loc_us-gaap_DeferredCompensationEquity_4116be1b-4cfa-4e8e-b1b2-999de0f44e3c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_d751fa06-cbfb-4914-9ec1-ac031ccf9106" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_4dae5a28-d4e8-487c-86a4-8038b9dbcb5e" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_d751fa06-cbfb-4914-9ec1-ac031ccf9106" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_fa102a81-279c-48dd-aaeb-140a2f70417f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_4dae5a28-d4e8-487c-86a4-8038b9dbcb5e" xlink:to="loc_us-gaap_StockholdersEquity_fa102a81-279c-48dd-aaeb-140a2f70417f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_db4ce895-b7a4-43c3-8ee2-56c8a3f3d870" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04f0ed13-6b02-4d80-b549-eaf7ced186cf" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_db4ce895-b7a4-43c3-8ee2-56c8a3f3d870" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/CONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="simple" xlink:href="bafn-20251231.xsd#CONSOLIDATEDBALANCESHEETSParenthetical"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/CONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_f36e7b3a-6a98-4cd1-b200-1e24f8195dec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_2a6945d1-2104-4765-9ec4-529acbe32435" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_f36e7b3a-6a98-4cd1-b200-1e24f8195dec" xlink:to="loc_us-gaap_StatementTable_2a6945d1-2104-4765-9ec4-529acbe32435" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_19f15b7d-c5a5-4f1b-8782-57a4102970a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_2a6945d1-2104-4765-9ec4-529acbe32435" xlink:to="loc_us-gaap_StatementClassOfStockAxis_19f15b7d-c5a5-4f1b-8782-57a4102970a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_19f15b7d-c5a5-4f1b-8782-57a4102970a9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_19f15b7d-c5a5-4f1b-8782-57a4102970a9" xlink:to="loc_us-gaap_ClassOfStockDomain_19f15b7d-c5a5-4f1b-8782-57a4102970a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_92d99d10-9014-42ac-8ea7-98a17b54cea9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_19f15b7d-c5a5-4f1b-8782-57a4102970a9" xlink:to="loc_us-gaap_ClassOfStockDomain_92d99d10-9014-42ac-8ea7-98a17b54cea9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_5f9cee7d-d751-4a20-8e34-91abd0058f0b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_92d99d10-9014-42ac-8ea7-98a17b54cea9" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_5f9cee7d-d751-4a20-8e34-91abd0058f0b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesBPreferredStockMember_e028adfc-8fb7-4737-90f9-f78f0f033566" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesBPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_92d99d10-9014-42ac-8ea7-98a17b54cea9" xlink:to="loc_us-gaap_SeriesBPreferredStockMember_e028adfc-8fb7-4737-90f9-f78f0f033566" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesCPreferredStockMember_fcdc2c6c-238a-4f92-8d61-63aba9e9135a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesCPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_92d99d10-9014-42ac-8ea7-98a17b54cea9" xlink:to="loc_us-gaap_SeriesCPreferredStockMember_fcdc2c6c-238a-4f92-8d61-63aba9e9135a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_a34e28a2-e8f8-4ddf-a138-70111fa429cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f36e7b3a-6a98-4cd1-b200-1e24f8195dec" xlink:to="loc_us-gaap_AssetsAbstract_a34e28a2-e8f8-4ddf-a138-70111fa429cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_8870741c-9910-4f35-9dc2-28478a63ba27" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_a34e28a2-e8f8-4ddf-a138-70111fa429cf" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_8870741c-9910-4f35-9dc2-28478a63ba27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest_90e7f015-1ca7-4ec7-8597-4fd9ab4d0332" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_a34e28a2-e8f8-4ddf-a138-70111fa429cf" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest_90e7f015-1ca7-4ec7-8597-4fd9ab4d0332" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_56707c32-243a-4c6b-8617-9dd56cfbd42d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_a34e28a2-e8f8-4ddf-a138-70111fa429cf" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_56707c32-243a-4c6b-8617-9dd56cfbd42d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_6174d5f8-ad8a-4d74-a264-f3631f42d076" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f36e7b3a-6a98-4cd1-b200-1e24f8195dec" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_6174d5f8-ad8a-4d74-a264-f3631f42d076" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_0b846213-fdba-4551-b2b0-36769ee20bfc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_6174d5f8-ad8a-4d74-a264-f3631f42d076" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_0b846213-fdba-4551-b2b0-36769ee20bfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_411fee90-2c6c-4bc3-8bcb-81674d872b06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_6174d5f8-ad8a-4d74-a264-f3631f42d076" xlink:to="loc_us-gaap_PreferredStockSharesIssued_411fee90-2c6c-4bc3-8bcb-81674d872b06" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_33e13f76-0725-4ff3-8cfa-c6d9ca344749" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_6174d5f8-ad8a-4d74-a264-f3631f42d076" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_33e13f76-0725-4ff3-8cfa-c6d9ca344749" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockLiquidationPreferenceValue_3d8ab63c-2719-4b52-81f2-4e44ee8a22bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockLiquidationPreferenceValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_6174d5f8-ad8a-4d74-a264-f3631f42d076" xlink:to="loc_us-gaap_PreferredStockLiquidationPreferenceValue_3d8ab63c-2719-4b52-81f2-4e44ee8a22bd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_0ae34017-04a4-42bd-88e7-5aa50112c77f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_6174d5f8-ad8a-4d74-a264-f3631f42d076" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_0ae34017-04a4-42bd-88e7-5aa50112c77f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_69acab63-b97a-45e8-af94-e9a4744538e5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_6174d5f8-ad8a-4d74-a264-f3631f42d076" xlink:to="loc_us-gaap_CommonStockSharesIssued_69acab63-b97a-45e8-af94-e9a4744538e5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_47869cc1-0345-4662-be32-b5339d74eeff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_6174d5f8-ad8a-4d74-a264-f3631f42d076" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_47869cc1-0345-4662-be32-b5339d74eeff" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITY" xlink:type="simple" xlink:href="bafn-20251231.xsd#CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_26b20ade-2d00-4d22-882e-acabae110644" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_7c2b6a2a-80f1-41f8-a63d-4c394c68b28c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_26b20ade-2d00-4d22-882e-acabae110644" xlink:to="loc_us-gaap_StatementTable_7c2b6a2a-80f1-41f8-a63d-4c394c68b28c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_95627273-1a0e-4da3-a98b-c5396efb93ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_7c2b6a2a-80f1-41f8-a63d-4c394c68b28c" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_95627273-1a0e-4da3-a98b-c5396efb93ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_95627273-1a0e-4da3-a98b-c5396efb93ed_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_95627273-1a0e-4da3-a98b-c5396efb93ed" xlink:to="loc_us-gaap_EquityComponentDomain_95627273-1a0e-4da3-a98b-c5396efb93ed_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_79f1b224-cf79-4d66-934a-2950a64e5eae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_95627273-1a0e-4da3-a98b-c5396efb93ed" xlink:to="loc_us-gaap_EquityComponentDomain_79f1b224-cf79-4d66-934a-2950a64e5eae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_47a5e272-2eba-4f71-8a92-6171170a40d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_79f1b224-cf79-4d66-934a-2950a64e5eae" xlink:to="loc_us-gaap_PreferredStockMember_47a5e272-2eba-4f71-8a92-6171170a40d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockIncludingAdditionalPaidInCapitalMember_c6932c53-8b45-4024-a6a8-a2a7378c355b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockIncludingAdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_79f1b224-cf79-4d66-934a-2950a64e5eae" xlink:to="loc_us-gaap_CommonStockIncludingAdditionalPaidInCapitalMember_c6932c53-8b45-4024-a6a8-a2a7378c355b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_b48d91cf-877e-4fe4-8bc2-3c49a4cb822a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_79f1b224-cf79-4d66-934a-2950a64e5eae" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_b48d91cf-877e-4fe4-8bc2-3c49a4cb822a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_2bfcb842-912e-49c6-b51e-f7deff74ef01" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_79f1b224-cf79-4d66-934a-2950a64e5eae" xlink:to="loc_us-gaap_RetainedEarningsMember_2bfcb842-912e-49c6-b51e-f7deff74ef01" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_732496c1-f489-4bce-91b6-ff9d1f53b011" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_7c2b6a2a-80f1-41f8-a63d-4c394c68b28c" xlink:to="loc_us-gaap_StatementClassOfStockAxis_732496c1-f489-4bce-91b6-ff9d1f53b011" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_732496c1-f489-4bce-91b6-ff9d1f53b011_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_732496c1-f489-4bce-91b6-ff9d1f53b011" xlink:to="loc_us-gaap_ClassOfStockDomain_732496c1-f489-4bce-91b6-ff9d1f53b011_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_029b4333-1eb8-42d6-ab28-3ca20f91df87" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_732496c1-f489-4bce-91b6-ff9d1f53b011" xlink:to="loc_us-gaap_ClassOfStockDomain_029b4333-1eb8-42d6-ab28-3ca20f91df87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_db864667-d874-441d-b74e-f7970f2f35e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_029b4333-1eb8-42d6-ab28-3ca20f91df87" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_db864667-d874-441d-b74e-f7970f2f35e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesBPreferredStockMember_64284c6b-0c09-46ac-aabe-5e002f998705" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesBPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_029b4333-1eb8-42d6-ab28-3ca20f91df87" xlink:to="loc_us-gaap_SeriesBPreferredStockMember_64284c6b-0c09-46ac-aabe-5e002f998705" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesCPreferredStockMember_56c2e036-9633-4b3b-bba7-e09720084089" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesCPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_029b4333-1eb8-42d6-ab28-3ca20f91df87" xlink:to="loc_us-gaap_SeriesCPreferredStockMember_56c2e036-9633-4b3b-bba7-e09720084089" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f009de93-540c-4877-a4fa-b6a13640d146" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_26b20ade-2d00-4d22-882e-acabae110644" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f009de93-540c-4877-a4fa-b6a13640d146" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_7413f87e-7fd7-43c4-8375-85f4bc3b3d0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f009de93-540c-4877-a4fa-b6a13640d146" xlink:to="loc_us-gaap_StockholdersEquity_7413f87e-7fd7-43c4-8375-85f4bc3b3d0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_b4cb8f88-c5df-4014-a7b3-6271b80d629e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f009de93-540c-4877-a4fa-b6a13640d146" xlink:to="loc_us-gaap_NetIncomeLoss_b4cb8f88-c5df-4014-a7b3-6271b80d629e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_73d80af4-ab6b-4cc4-a727-12d1d87a6291" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f009de93-540c-4877-a4fa-b6a13640d146" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_73d80af4-ab6b-4cc4-a727-12d1d87a6291" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_1a48e186-90a3-4a66-827d-79fd6a4cb7a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f009de93-540c-4877-a4fa-b6a13640d146" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_1a48e186-90a3-4a66-827d-79fd6a4cb7a5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_UnearnedEmployeeStockOwnershipPlanSharesAllocation_8dbb5c8a-dc15-438b-9b30-42855252271a" xlink:href="bafn-20251231.xsd#bafn_UnearnedEmployeeStockOwnershipPlanSharesAllocation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f009de93-540c-4877-a4fa-b6a13640d146" xlink:to="loc_bafn_UnearnedEmployeeStockOwnershipPlanSharesAllocation_8dbb5c8a-dc15-438b-9b30-42855252271a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharebasedCompensationAbstract_7b491cd4-0696-41c6-9efd-78a4c74427f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharebasedCompensationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f009de93-540c-4877-a4fa-b6a13640d146" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharebasedCompensationAbstract_7b491cd4-0696-41c6-9efd-78a4c74427f8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_54b9dbef-5c70-40aa-b339-6e63256cdcba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharebasedCompensationAbstract_7b491cd4-0696-41c6-9efd-78a4c74427f8" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_54b9dbef-5c70-40aa-b339-6e63256cdcba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_f2449b24-269c-4efb-b047-e61cbbb01204" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharebasedCompensationAbstract_7b491cd4-0696-41c6-9efd-78a4c74427f8" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_f2449b24-269c-4efb-b047-e61cbbb01204" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_2a7cc80e-378f-4f4e-b771-6c17722dd5dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f009de93-540c-4877-a4fa-b6a13640d146" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_2a7cc80e-378f-4f4e-b771-6c17722dd5dc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsAbstract_9305e8e8-5a3b-4c7b-accc-58cddd93ecb3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f009de93-540c-4877-a4fa-b6a13640d146" xlink:to="loc_us-gaap_DividendsAbstract_9305e8e8-5a3b-4c7b-accc-58cddd93ecb3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStockCash_ba46afe3-f342-4f77-b61d-abaee01a8c93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsPreferredStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsAbstract_9305e8e8-5a3b-4c7b-accc-58cddd93ecb3" xlink:to="loc_us-gaap_DividendsPreferredStockCash_ba46afe3-f342-4f77-b61d-abaee01a8c93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_c32946ee-ba93-4063-bd5a-b5c193a85f7c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsAbstract_9305e8e8-5a3b-4c7b-accc-58cddd93ecb3" xlink:to="loc_us-gaap_DividendsCommonStockCash_c32946ee-ba93-4063-bd5a-b5c193a85f7c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_0ea61060-3b39-4c39-8346-1ac3f291d40e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESNarrativeDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/BASISOFPRESENTATIONANDSUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_b9a86695-bb50-4f60-ac5f-5d84a60c3c52" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_b9a86695-bb50-4f60-ac5f-5d84a60c3c52" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_11201d80-f03b-40b5-b1d8-cb548e04b2da" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_b9a86695-bb50-4f60-ac5f-5d84a60c3c52" xlink:to="loc_srt_RangeAxis_11201d80-f03b-40b5-b1d8-cb548e04b2da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_11201d80-f03b-40b5-b1d8-cb548e04b2da_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_11201d80-f03b-40b5-b1d8-cb548e04b2da" xlink:to="loc_srt_RangeMember_11201d80-f03b-40b5-b1d8-cb548e04b2da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_4c20bcc2-d117-4b83-a31c-13589579925c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_11201d80-f03b-40b5-b1d8-cb548e04b2da" xlink:to="loc_srt_RangeMember_4c20bcc2-d117-4b83-a31c-13589579925c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_22193a43-467f-4402-9887-31ad0e950651" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4c20bcc2-d117-4b83-a31c-13589579925c" xlink:to="loc_srt_MinimumMember_22193a43-467f-4402-9887-31ad0e950651" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_80756b5e-1928-4a49-8807-7faf48e8e3cc" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4c20bcc2-d117-4b83-a31c-13589579925c" xlink:to="loc_srt_MaximumMember_80756b5e-1928-4a49-8807-7faf48e8e3cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_EmployerMatchingContributionTierAxisAxis_019c1a37-5efe-7f84-b13d-3554170131af" xlink:href="bafn-20251231.xsd#bafn_EmployerMatchingContributionTierAxisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_b9a86695-bb50-4f60-ac5f-5d84a60c3c52" xlink:to="loc_bafn_EmployerMatchingContributionTierAxisAxis_019c1a37-5efe-7f84-b13d-3554170131af" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_EmployerMatchingContributionTierAxisDomain_019c1a37-5efe-7f84-b13d-3554170131af_default" xlink:href="bafn-20251231.xsd#bafn_EmployerMatchingContributionTierAxisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bafn_EmployerMatchingContributionTierAxisAxis_019c1a37-5efe-7f84-b13d-3554170131af" xlink:to="loc_bafn_EmployerMatchingContributionTierAxisDomain_019c1a37-5efe-7f84-b13d-3554170131af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_EmployerMatchingContributionTierAxisDomain_019c1a37-5efe-7711-bd61-7ed9132a95c8" xlink:href="bafn-20251231.xsd#bafn_EmployerMatchingContributionTierAxisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bafn_EmployerMatchingContributionTierAxisAxis_019c1a37-5efe-7f84-b13d-3554170131af" xlink:to="loc_bafn_EmployerMatchingContributionTierAxisDomain_019c1a37-5efe-7711-bd61-7ed9132a95c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_TierOneMember_019c1a37-5efe-744a-8fac-c8af4b12261f" xlink:href="bafn-20251231.xsd#bafn_TierOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_EmployerMatchingContributionTierAxisDomain_019c1a37-5efe-7711-bd61-7ed9132a95c8" xlink:to="loc_bafn_TierOneMember_019c1a37-5efe-744a-8fac-c8af4b12261f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_TierTwoMember_019c1a37-5efe-700e-a185-2db578f79153" xlink:href="bafn-20251231.xsd#bafn_TierTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_EmployerMatchingContributionTierAxisDomain_019c1a37-5efe-7711-bd61-7ed9132a95c8" xlink:to="loc_bafn_TierTwoMember_019c1a37-5efe-700e-a185-2db578f79153" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019c1a37-5efe-7df5-9a9c-59aa381d124c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_b9a86695-bb50-4f60-ac5f-5d84a60c3c52" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019c1a37-5efe-7df5-9a9c-59aa381d124c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019c1a37-5efe-7df5-9a9c-59aa381d124c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019c1a37-5efe-7df5-9a9c-59aa381d124c" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019c1a37-5efe-7df5-9a9c-59aa381d124c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019c1a37-5efe-708e-973c-e91271c9a46e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019c1a37-5efe-7df5-9a9c-59aa381d124c" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019c1a37-5efe-708e-973c-e91271c9a46e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019c1a37-5efe-7833-820b-cdd9f802ac7c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019c1a37-5efe-708e-973c-e91271c9a46e" xlink:to="loc_us-gaap_SubsequentEventMember_019c1a37-5efe-7833-820b-cdd9f802ac7c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_524bb8ef-5020-44f4-b0b7-e6f7f1534048" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_b9a86695-bb50-4f60-ac5f-5d84a60c3c52" xlink:to="loc_us-gaap_PlanNameAxis_524bb8ef-5020-44f4-b0b7-e6f7f1534048" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_524bb8ef-5020-44f4-b0b7-e6f7f1534048_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_524bb8ef-5020-44f4-b0b7-e6f7f1534048" xlink:to="loc_us-gaap_PlanNameDomain_524bb8ef-5020-44f4-b0b7-e6f7f1534048_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_338a28ce-3c21-4ebe-a7df-bfc5eaf8a5bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_524bb8ef-5020-44f4-b0b7-e6f7f1534048" xlink:to="loc_us-gaap_PlanNameDomain_338a28ce-3c21-4ebe-a7df-bfc5eaf8a5bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_NonQualifiedStockPurchasePlanMember_410a17c7-6c30-40d5-8856-7f0b8ef926b6" xlink:href="bafn-20251231.xsd#bafn_NonQualifiedStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_338a28ce-3c21-4ebe-a7df-bfc5eaf8a5bc" xlink:to="loc_bafn_NonQualifiedStockPurchasePlanMember_410a17c7-6c30-40d5-8856-7f0b8ef926b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_5c57cd4f-8445-4155-938e-0bc5e3974cbf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_b9a86695-bb50-4f60-ac5f-5d84a60c3c52" xlink:to="loc_us-gaap_StatementClassOfStockAxis_5c57cd4f-8445-4155-938e-0bc5e3974cbf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_5c57cd4f-8445-4155-938e-0bc5e3974cbf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_5c57cd4f-8445-4155-938e-0bc5e3974cbf" xlink:to="loc_us-gaap_ClassOfStockDomain_5c57cd4f-8445-4155-938e-0bc5e3974cbf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_83fdb9c6-9011-485f-bafc-bded82c837cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_5c57cd4f-8445-4155-938e-0bc5e3974cbf" xlink:to="loc_us-gaap_ClassOfStockDomain_83fdb9c6-9011-485f-bafc-bded82c837cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_f7110925-f038-46f6-a70a-e5cd19cebf40" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_83fdb9c6-9011-485f-bafc-bded82c837cc" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_f7110925-f038-46f6-a70a-e5cd19cebf40" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesBPreferredStockMember_83cf7dd7-8d15-4d19-a59d-76221fc9c29c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesBPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_83fdb9c6-9011-485f-bafc-bded82c837cc" xlink:to="loc_us-gaap_SeriesBPreferredStockMember_83cf7dd7-8d15-4d19-a59d-76221fc9c29c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesCPreferredStockMember_f3447b09-f89c-43d4-9034-8e75a6da3621" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesCPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_83fdb9c6-9011-485f-bafc-bded82c837cc" xlink:to="loc_us-gaap_SeriesCPreferredStockMember_f3447b09-f89c-43d4-9034-8e75a6da3621" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_90a52b2c-31a7-4488-ad27-64bd09c4b6c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_b9a86695-bb50-4f60-ac5f-5d84a60c3c52" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_90a52b2c-31a7-4488-ad27-64bd09c4b6c0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_90a52b2c-31a7-4488-ad27-64bd09c4b6c0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_90a52b2c-31a7-4488-ad27-64bd09c4b6c0" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_90a52b2c-31a7-4488-ad27-64bd09c4b6c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3bb508a6-3fc4-4075-98be-533507be619d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_90a52b2c-31a7-4488-ad27-64bd09c4b6c0" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3bb508a6-3fc4-4075-98be-533507be619d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingMember_9ac570e9-630c-45f5-8ee3-0786fbd54c2c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3bb508a6-3fc4-4075-98be-533507be619d" xlink:to="loc_us-gaap_BuildingMember_9ac570e9-630c-45f5-8ee3-0786fbd54c2c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_33ed52da-0c90-46b8-9642-2ab33adaade4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3bb508a6-3fc4-4075-98be-533507be619d" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_33ed52da-0c90-46b8-9642-2ab33adaade4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_FurnitureFixturesAndEquipmentMember_7b7e1226-32fc-42fb-8ae3-f601c7087461" xlink:href="bafn-20251231.xsd#bafn_FurnitureFixturesAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3bb508a6-3fc4-4075-98be-533507be619d" xlink:to="loc_bafn_FurnitureFixturesAndEquipmentMember_7b7e1226-32fc-42fb-8ae3-f601c7087461" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_208f6167-68bf-491c-9894-fdd66adff826" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_us-gaap_NumberOfOperatingSegments_208f6167-68bf-491c-9894-fdd66adff826" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_13aec8f2-37b7-4a73-9c7d-005abf44f6ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_13aec8f2-37b7-4a73-9c7d-005abf44f6ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_0d4546f5-500a-4ee5-8747-35d9694f79f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseRemainingLeaseTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_0d4546f5-500a-4ee5-8747-35d9694f79f9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_900eda00-e3c5-496f-9acf-f37d738e4ca4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_900eda00-e3c5-496f-9acf-f37d738e4ca4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_DefinedContributionPlanEmployerContributionPercentOfEmployeesGrossPay_e7f1502b-d8d9-451a-9eb5-bf4c3c3590b6" xlink:href="bafn-20251231.xsd#bafn_DefinedContributionPlanEmployerContributionPercentOfEmployeesGrossPay"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_bafn_DefinedContributionPlanEmployerContributionPercentOfEmployeesGrossPay_e7f1502b-d8d9-451a-9eb5-bf4c3c3590b6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_019c1a37-5efe-7044-92c4-52c2f5ddbd23" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_019c1a37-5efe-7044-92c4-52c2f5ddbd23" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_019c1a37-5efe-7bde-acaa-7ee83d291f41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_019c1a37-5efe-7bde-acaa-7ee83d291f41" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate_89bf804b-f05c-4f9b-9ab8-9e5ce817f79a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate_89bf804b-f05c-4f9b-9ab8-9e5ce817f79a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendRatePercentage_ba988680-d79f-4844-9849-decc2829e7ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockDividendRatePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_us-gaap_PreferredStockDividendRatePercentage_ba988680-d79f-4844-9849-decc2829e7ff" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_PreferredStockDividendRatePercentageIfSharesNotRedeemedByTenthAnniversary_fc6c82ea-13c7-4bb5-8a43-6b47a05f79ad" xlink:href="bafn-20251231.xsd#bafn_PreferredStockDividendRatePercentageIfSharesNotRedeemedByTenthAnniversary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_bafn_PreferredStockDividendRatePercentageIfSharesNotRedeemedByTenthAnniversary_fc6c82ea-13c7-4bb5-8a43-6b47a05f79ad" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockAmountOfPreferredDividendsInArrears_019c1184-eb80-71a4-a9e1-b6a0cc6b3c3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockAmountOfPreferredDividendsInArrears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_7088a7ff-7196-4f06-bb26-4fc08a9b808e" xlink:to="loc_us-gaap_PreferredStockAmountOfPreferredDividendsInArrears_019c1184-eb80-71a4-a9e1-b6a0cc6b3c3c" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/DISCONTINUEDOPERATIONSNarrativeDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#DISCONTINUEDOPERATIONSNarrativeDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/DISCONTINUEDOPERATIONSNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_ca58f042-277a-432c-a745-f4310bc05591" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_598694ce-633c-481a-a2df-9eef8200611b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_ca58f042-277a-432c-a745-f4310bc05591" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_598694ce-633c-481a-a2df-9eef8200611b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_405d9104-26ea-44c0-bf58-01f4ac943d3d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_598694ce-633c-481a-a2df-9eef8200611b" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_405d9104-26ea-44c0-bf58-01f4ac943d3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_405d9104-26ea-44c0-bf58-01f4ac943d3d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_405d9104-26ea-44c0-bf58-01f4ac943d3d" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_405d9104-26ea-44c0-bf58-01f4ac943d3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_a701e963-af9f-4a5b-9fcc-fbdbc83ef91f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_405d9104-26ea-44c0-bf58-01f4ac943d3d" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_a701e963-af9f-4a5b-9fcc-fbdbc83ef91f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_c6c48a11-25ba-4a18-a40e-83ebca0e2c0a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_a701e963-af9f-4a5b-9fcc-fbdbc83ef91f" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_c6c48a11-25ba-4a18-a40e-83ebca0e2c0a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_23257f8d-5213-4396-ae7a-6dd4d7f448bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_598694ce-633c-481a-a2df-9eef8200611b" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_23257f8d-5213-4396-ae7a-6dd4d7f448bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_23257f8d-5213-4396-ae7a-6dd4d7f448bf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_23257f8d-5213-4396-ae7a-6dd4d7f448bf" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_23257f8d-5213-4396-ae7a-6dd4d7f448bf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3aae9ab7-a270-4783-936a-d878d365eb87" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_23257f8d-5213-4396-ae7a-6dd4d7f448bf" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3aae9ab7-a270-4783-936a-d878d365eb87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_NationwideResidentialMortgageLoanProductionOperationsMember_360dde2f-7e0a-4c47-b619-36457dc3b8ad" xlink:href="bafn-20251231.xsd#bafn_NationwideResidentialMortgageLoanProductionOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3aae9ab7-a270-4783-936a-d878d365eb87" xlink:to="loc_bafn_NationwideResidentialMortgageLoanProductionOperationsMember_360dde2f-7e0a-4c47-b619-36457dc3b8ad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_607c9d2e-6505-44e0-8883-97394fb07385" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_ca58f042-277a-432c-a745-f4310bc05591" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_607c9d2e-6505-44e0-8883-97394fb07385" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_d5baf84b-508f-4bc8-aa9c-d47d74ed16d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_ca58f042-277a-432c-a745-f4310bc05591" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_d5baf84b-508f-4bc8-aa9c-d47d74ed16d0" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/DISCONTINUEDOPERATIONSScheduleofOperatingResultsoftheDiscontinuedOperationsoftheSba7aLendingandResidentialMortgageLendingDivisionDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#DISCONTINUEDOPERATIONSScheduleofOperatingResultsoftheDiscontinuedOperationsoftheSba7aLendingandResidentialMortgageLendingDivisionDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/DISCONTINUEDOPERATIONSScheduleofOperatingResultsoftheDiscontinuedOperationsoftheSba7aLendingandResidentialMortgageLendingDivisionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_40d0f76b-b6ee-4239-bb6f-d8c53297ec4b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_7c58a138-3037-4093-8f5f-c5fd90350cdc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_40d0f76b-b6ee-4239-bb6f-d8c53297ec4b" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_7c58a138-3037-4093-8f5f-c5fd90350cdc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_6af6b0ff-82e1-4727-9e4f-941f3bf2dc39" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_7c58a138-3037-4093-8f5f-c5fd90350cdc" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_6af6b0ff-82e1-4727-9e4f-941f3bf2dc39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_6af6b0ff-82e1-4727-9e4f-941f3bf2dc39_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_6af6b0ff-82e1-4727-9e4f-941f3bf2dc39" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_6af6b0ff-82e1-4727-9e4f-941f3bf2dc39_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_35030493-62c4-4a12-aad6-ddac0c4360df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_6af6b0ff-82e1-4727-9e4f-941f3bf2dc39" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_35030493-62c4-4a12-aad6-ddac0c4360df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_aa609ce9-317a-4184-b07f-cbcc199d79dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_35030493-62c4-4a12-aad6-ddac0c4360df" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_aa609ce9-317a-4184-b07f-cbcc199d79dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9f552779-73d5-4b3e-9f21-b9647a571c41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_7c58a138-3037-4093-8f5f-c5fd90350cdc" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9f552779-73d5-4b3e-9f21-b9647a571c41" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_9f552779-73d5-4b3e-9f21-b9647a571c41_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9f552779-73d5-4b3e-9f21-b9647a571c41" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_9f552779-73d5-4b3e-9f21-b9647a571c41_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_bf568245-f964-43e3-a767-c1e13419bc87" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9f552779-73d5-4b3e-9f21-b9647a571c41" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_bf568245-f964-43e3-a767-c1e13419bc87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_NationwideResidentialMortgageLoanProductionOperationsMember_c165bdd9-1f85-4d18-bdc3-d2359b45a744" xlink:href="bafn-20251231.xsd#bafn_NationwideResidentialMortgageLoanProductionOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_bf568245-f964-43e3-a767-c1e13419bc87" xlink:to="loc_bafn_NationwideResidentialMortgageLoanProductionOperationsMember_c165bdd9-1f85-4d18-bdc3-d2359b45a744" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_DisposalGroupIncludingDiscontinuedOperationNoninterestIncome_521cf57c-f906-42ac-a68e-4a1657109515" xlink:href="bafn-20251231.xsd#bafn_DisposalGroupIncludingDiscontinuedOperationNoninterestIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_40d0f76b-b6ee-4239-bb6f-d8c53297ec4b" xlink:to="loc_bafn_DisposalGroupIncludingDiscontinuedOperationNoninterestIncome_521cf57c-f906-42ac-a68e-4a1657109515" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_ee9214de-c3e5-49c7-963b-ea5f90d11fca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_40d0f76b-b6ee-4239-bb6f-d8c53297ec4b" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_ee9214de-c3e5-49c7-963b-ea5f90d11fca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherExpense_0983357d-bc54-41c7-b0c1-caef9d94afa4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_40d0f76b-b6ee-4239-bb6f-d8c53297ec4b" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherExpense_0983357d-bc54-41c7-b0c1-caef9d94afa4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_aecf2928-f13f-4633-bb38-7b86d66aab64" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_40d0f76b-b6ee-4239-bb6f-d8c53297ec4b" xlink:to="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_aecf2928-f13f-4633-bb38-7b86d66aab64" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_4dbfdb4f-f179-4f67-9a55-54de11e5fd1f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_40d0f76b-b6ee-4239-bb6f-d8c53297ec4b" xlink:to="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_4dbfdb4f-f179-4f67-9a55-54de11e5fd1f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_0607ef9f-cd05-4d38-9892-ccca758a2b2b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_40d0f76b-b6ee-4239-bb6f-d8c53297ec4b" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_0607ef9f-cd05-4d38-9892-ccca758a2b2b" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/INVESTMENTSECURITIESScheduleofDebtSecuritiesAvailableforSaleandHeldtoMaturityDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#INVESTMENTSECURITIESScheduleofDebtSecuritiesAvailableforSaleandHeldtoMaturityDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/INVESTMENTSECURITIESScheduleofDebtSecuritiesAvailableforSaleandHeldtoMaturityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_548a0d9d-1d1e-46bd-85ca-8e45dc9fba0f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_867d42fa-aa70-4bc8-ac57-01eb8c5c1acc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_548a0d9d-1d1e-46bd-85ca-8e45dc9fba0f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_867d42fa-aa70-4bc8-ac57-01eb8c5c1acc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_99321f09-23b8-4802-9b28-1f8db704c7b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_867d42fa-aa70-4bc8-ac57-01eb8c5c1acc" xlink:to="loc_us-gaap_FinancialInstrumentAxis_99321f09-23b8-4802-9b28-1f8db704c7b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_99321f09-23b8-4802-9b28-1f8db704c7b3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_99321f09-23b8-4802-9b28-1f8db704c7b3" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_99321f09-23b8-4802-9b28-1f8db704c7b3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f1aff35f-f0c0-4027-9fe8-8047a032048b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_99321f09-23b8-4802-9b28-1f8db704c7b3" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f1aff35f-f0c0-4027-9fe8-8047a032048b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_81417c44-8a64-4054-b6f4-4a6ad0d1ee72" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f1aff35f-f0c0-4027-9fe8-8047a032048b" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_81417c44-8a64-4054-b6f4-4a6ad0d1ee72" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_54968337-c7c4-494e-8edf-4b07ef5ff486" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f1aff35f-f0c0-4027-9fe8-8047a032048b" xlink:to="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_54968337-c7c4-494e-8edf-4b07ef5ff486" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedLoanObligationsMember_9e4d5474-cadd-47c2-bd29-e460fe27bf28" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralizedLoanObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f1aff35f-f0c0-4027-9fe8-8047a032048b" xlink:to="loc_us-gaap_CollateralizedLoanObligationsMember_9e4d5474-cadd-47c2-bd29-e460fe27bf28" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_b978e300-eb07-4a3c-9597-a9542b6273f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateBondSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f1aff35f-f0c0-4027-9fe8-8047a032048b" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_b978e300-eb07-4a3c-9597-a9542b6273f8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_4e162d28-f25e-446b-ae1a-99d0a4cb2f26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_548a0d9d-1d1e-46bd-85ca-8e45dc9fba0f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_4e162d28-f25e-446b-ae1a-99d0a4cb2f26" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_32023baf-c75f-48bb-9516-1f88120149b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_548a0d9d-1d1e-46bd-85ca-8e45dc9fba0f" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_32023baf-c75f-48bb-9516-1f88120149b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_eed45fe8-7867-4493-a8df-19340395c8c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_548a0d9d-1d1e-46bd-85ca-8e45dc9fba0f" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_eed45fe8-7867-4493-a8df-19340395c8c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_3148eeb6-0191-4e73-8379-e46baf8253ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_548a0d9d-1d1e-46bd-85ca-8e45dc9fba0f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_3148eeb6-0191-4e73-8379-e46baf8253ce" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_162d3fb1-ba05-4491-ba37-51a616194158" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_18df7a06-c9a4-425d-85a3-453ac6b583e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_162d3fb1-ba05-4491-ba37-51a616194158" xlink:to="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_18df7a06-c9a4-425d-85a3-453ac6b583e3" xlink:type="arc" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_8bf8ea6b-a475-4a6c-bbd7-757b1dc94e73" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_18df7a06-c9a4-425d-85a3-453ac6b583e3" xlink:to="loc_us-gaap_FinancialInstrumentAxis_8bf8ea6b-a475-4a6c-bbd7-757b1dc94e73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8bf8ea6b-a475-4a6c-bbd7-757b1dc94e73_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_05d0ee0c-596e-4185-bdea-49ee8da76dcb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_93b5a411-4c4c-4d90-9c91-031ad43d02d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateBondSecuritiesMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss_5ba1141f-8be7-4eab-a5a8-91552bcd6a31" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_162d3fb1-ba05-4491-ba37-51a616194158" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss_5ba1141f-8be7-4eab-a5a8-91552bcd6a31" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain_822b4eb6-a9e6-491e-9403-a7cac9e169db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_162d3fb1-ba05-4491-ba37-51a616194158" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain_822b4eb6-a9e6-491e-9403-a7cac9e169db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss_fb5d2737-3b72-4468-bbd7-821d13b11f93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_162d3fb1-ba05-4491-ba37-51a616194158" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss_fb5d2737-3b72-4468-bbd7-821d13b11f93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_3b089022-fa04-4340-880d-fbb48ec2f0bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_162d3fb1-ba05-4491-ba37-51a616194158" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_3b089022-fa04-4340-880d-fbb48ec2f0bd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest_de5d892d-7a30-46f9-86f4-a28317e87705" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_162d3fb1-ba05-4491-ba37-51a616194158" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest_de5d892d-7a30-46f9-86f4-a28317e87705" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/INVESTMENTSECURITIESScheduleofInvestmentSecuritiesWithUnrealizedLossesDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#INVESTMENTSECURITIESScheduleofInvestmentSecuritiesWithUnrealizedLossesDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/INVESTMENTSECURITIESScheduleofInvestmentSecuritiesWithUnrealizedLossesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2fb1aa89-e130-44fe-b8d3-b06a7280db3a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_3e79f104-afab-42a4-a764-618956fdf2e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2fb1aa89-e130-44fe-b8d3-b06a7280db3a" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_3e79f104-afab-42a4-a764-618956fdf2e0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_76c26083-1411-44b1-acdf-6d9ad674fb65" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_3e79f104-afab-42a4-a764-618956fdf2e0" xlink:to="loc_us-gaap_FinancialInstrumentAxis_76c26083-1411-44b1-acdf-6d9ad674fb65" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_76c26083-1411-44b1-acdf-6d9ad674fb65_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_76c26083-1411-44b1-acdf-6d9ad674fb65" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_76c26083-1411-44b1-acdf-6d9ad674fb65_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4771f367-e11c-4117-a90a-e43b681e253b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_76c26083-1411-44b1-acdf-6d9ad674fb65" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4771f367-e11c-4117-a90a-e43b681e253b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_372a9666-c135-4adf-8d92-27f59c6bf572" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4771f367-e11c-4117-a90a-e43b681e253b" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_372a9666-c135-4adf-8d92-27f59c6bf572" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_c130a1a8-9cae-4491-a2e8-3316791545fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4771f367-e11c-4117-a90a-e43b681e253b" xlink:to="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_c130a1a8-9cae-4491-a2e8-3316791545fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralizedLoanObligationsMember_ca490f8a-defb-4a92-bcce-1af6c12bab91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralizedLoanObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4771f367-e11c-4117-a90a-e43b681e253b" xlink:to="loc_us-gaap_CollateralizedLoanObligationsMember_ca490f8a-defb-4a92-bcce-1af6c12bab91" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_019c3200-bd56-7357-9fb6-1516dd808f53" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateBondSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4771f367-e11c-4117-a90a-e43b681e253b" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_019c3200-bd56-7357-9fb6-1516dd808f53" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_8a32087a-0544-453d-81d6-071234c7010a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2fb1aa89-e130-44fe-b8d3-b06a7280db3a" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_8a32087a-0544-453d-81d6-071234c7010a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_adadb922-d194-450f-b443-5b0498919f7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_8a32087a-0544-453d-81d6-071234c7010a" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_adadb922-d194-450f-b443-5b0498919f7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_0a612dd9-e341-44b5-b2a9-3ffafb3dc426" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_8a32087a-0544-453d-81d6-071234c7010a" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_0a612dd9-e341-44b5-b2a9-3ffafb3dc426" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_c96e1c9e-d523-4f85-a7a3-17934fc98229" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_8a32087a-0544-453d-81d6-071234c7010a" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_c96e1c9e-d523-4f85-a7a3-17934fc98229" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_c743b8aa-706b-46d0-a475-2d267afe33eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_8a32087a-0544-453d-81d6-071234c7010a" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_c743b8aa-706b-46d0-a475-2d267afe33eb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_e4aa3dcd-2579-4dfc-8ec8-88a968b895f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_8a32087a-0544-453d-81d6-071234c7010a" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_e4aa3dcd-2579-4dfc-8ec8-88a968b895f6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_29c2d92b-5b78-46ef-8c0e-db25223c8bc7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_8a32087a-0544-453d-81d6-071234c7010a" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_29c2d92b-5b78-46ef-8c0e-db25223c8bc7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions_d44bffdc-9cd6-4179-9913-2296f61fcc95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_8a32087a-0544-453d-81d6-071234c7010a" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions_d44bffdc-9cd6-4179-9913-2296f61fcc95" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_c323e9a1-7919-4951-9501-4b2469d7136f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_ad6a7b9d-2baf-4164-afee-8a19a1bdde90" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_c323e9a1-7919-4951-9501-4b2469d7136f" xlink:to="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_ad6a7b9d-2baf-4164-afee-8a19a1bdde90" xlink:type="arc" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_87fce5ef-be96-49ba-8dc4-926198723965" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_ad6a7b9d-2baf-4164-afee-8a19a1bdde90" xlink:to="loc_us-gaap_FinancialInstrumentAxis_87fce5ef-be96-49ba-8dc4-926198723965" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_87fce5ef-be96-49ba-8dc4-926198723965_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dbd304d1-fec5-4940-b167-ffadcb4b7543" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_a2816c5a-eb5e-4065-a705-607fc78aa689" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateBondSecuritiesMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_350a8d66-0c1d-404d-821f-038f5b7e5040" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_c323e9a1-7919-4951-9501-4b2469d7136f" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_350a8d66-0c1d-404d-821f-038f5b7e5040" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_a499a93b-bd0d-4a03-911f-4224906a50e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_350a8d66-0c1d-404d-821f-038f5b7e5040" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_a499a93b-bd0d-4a03-911f-4224906a50e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_a3313b8c-d226-4de1-9a48-5c82d89bd91f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_350a8d66-0c1d-404d-821f-038f5b7e5040" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_a3313b8c-d226-4de1-9a48-5c82d89bd91f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_358a021f-1c0a-45ae-9569-ce48a1117922" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_350a8d66-0c1d-404d-821f-038f5b7e5040" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_358a021f-1c0a-45ae-9569-ce48a1117922" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_f35171e3-858e-4df8-b38b-ce621fdf404e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_350a8d66-0c1d-404d-821f-038f5b7e5040" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_f35171e3-858e-4df8-b38b-ce621fdf404e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue_3988c89a-2a29-4ecd-8f5f-7c2b1ced67d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_350a8d66-0c1d-404d-821f-038f5b7e5040" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue_3988c89a-2a29-4ecd-8f5f-7c2b1ced67d2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss_472d70d2-608f-4259-af2b-776e5273f0e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_350a8d66-0c1d-404d-821f-038f5b7e5040" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss_472d70d2-608f-4259-af2b-776e5273f0e9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions_bb1f83ff-1044-4402-8224-1272b8a5ebcc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_350a8d66-0c1d-404d-821f-038f5b7e5040" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions_bb1f83ff-1044-4402-8224-1272b8a5ebcc" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/LOANSDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#LOANSDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/LOANSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_295c5199-0243-489f-9365-7b6bd3bf0d1e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_01018e88-f4ad-4962-8ac9-ce0742b9239d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_295c5199-0243-489f-9365-7b6bd3bf0d1e" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_01018e88-f4ad-4962-8ac9-ce0742b9239d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_16700af0-e86e-4d70-9618-e484b2575e2c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_01018e88-f4ad-4962-8ac9-ce0742b9239d" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_16700af0-e86e-4d70-9618-e484b2575e2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_16700af0-e86e-4d70-9618-e484b2575e2c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_16700af0-e86e-4d70-9618-e484b2575e2c" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_16700af0-e86e-4d70-9618-e484b2575e2c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_fcb2e735-ac35-40e4-a81a-27865141f79f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_16700af0-e86e-4d70-9618-e484b2575e2c" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_fcb2e735-ac35-40e4-a81a-27865141f79f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ResidentialRealEstateSegmentMember_0208fab8-3043-4fab-a78e-6db688930450" xlink:href="bafn-20251231.xsd#bafn_ResidentialRealEstateSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_fcb2e735-ac35-40e4-a81a-27865141f79f" xlink:to="loc_bafn_ResidentialRealEstateSegmentMember_0208fab8-3043-4fab-a78e-6db688930450" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_e15367ab-e7ad-444f-bdf5-9bdf3edc75c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_fcb2e735-ac35-40e4-a81a-27865141f79f" xlink:to="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_e15367ab-e7ad-444f-bdf5-9bdf3edc75c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConstructionAndLandRealEstateSegmentMember_2f54344e-812e-4fa9-b65b-c5d8caa5e8bc" xlink:href="bafn-20251231.xsd#bafn_ConstructionAndLandRealEstateSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_fcb2e735-ac35-40e4-a81a-27865141f79f" xlink:to="loc_bafn_ConstructionAndLandRealEstateSegmentMember_2f54344e-812e-4fa9-b65b-c5d8caa5e8bc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_CommercialAndIndustrialSegmentMember_9c5181fe-f2e9-4e8b-b23f-6c19a64a5689" xlink:href="bafn-20251231.xsd#bafn_CommercialAndIndustrialSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_fcb2e735-ac35-40e4-a81a-27865141f79f" xlink:to="loc_bafn_CommercialAndIndustrialSegmentMember_9c5181fe-f2e9-4e8b-b23f-6c19a64a5689" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_CommercialAndIndustrialPPPSegmentMember_1f9c893f-0acf-4ad2-85f3-a20432b3f0d7" xlink:href="bafn-20251231.xsd#bafn_CommercialAndIndustrialPPPSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_fcb2e735-ac35-40e4-a81a-27865141f79f" xlink:to="loc_bafn_CommercialAndIndustrialPPPSegmentMember_1f9c893f-0acf-4ad2-85f3-a20432b3f0d7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConsumerAndOtherSegmentMember_911f9240-f358-402c-859d-68b09e2f9741" xlink:href="bafn-20251231.xsd#bafn_ConsumerAndOtherSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_fcb2e735-ac35-40e4-a81a-27865141f79f" xlink:to="loc_bafn_ConsumerAndOtherSegmentMember_911f9240-f358-402c-859d-68b09e2f9741" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess_1c11fe6a-c07b-496a-8441-9668b5e7d05c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_295c5199-0243-489f-9365-7b6bd3bf0d1e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess_1c11fe6a-c07b-496a-8441-9668b5e7d05c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableUnamortizedLoanFeeCost_a2c04432-18e3-410e-83d1-4df7561469b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableUnamortizedLoanFeeCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_295c5199-0243-489f-9365-7b6bd3bf0d1e" xlink:to="loc_us-gaap_FinancingReceivableUnamortizedLoanFeeCost_a2c04432-18e3-410e-83d1-4df7561469b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_FinancingReceivableDiscountOnLoansSold_916aedd5-1c32-455e-8b5d-4a3b07b6e7e5" xlink:href="bafn-20251231.xsd#bafn_FinancingReceivableDiscountOnLoansSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_295c5199-0243-489f-9365-7b6bd3bf0d1e" xlink:to="loc_bafn_FinancingReceivableDiscountOnLoansSold_916aedd5-1c32-455e-8b5d-4a3b07b6e7e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableUnamortizedPurchasePremiumDiscount_2d8e58fc-e48a-4450-8317-e5b974da1cf8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableUnamortizedPurchasePremiumDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_295c5199-0243-489f-9365-7b6bd3bf0d1e" xlink:to="loc_us-gaap_FinancingReceivableUnamortizedPurchasePremiumDiscount_2d8e58fc-e48a-4450-8317-e5b974da1cf8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_30882019-697f-4167-8c2d-d849147a109d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_295c5199-0243-489f-9365-7b6bd3bf0d1e" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_30882019-697f-4167-8c2d-d849147a109d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_67cdeb27-be49-4e8f-99b3-9ca87c01d643" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_295c5199-0243-489f-9365-7b6bd3bf0d1e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_67cdeb27-be49-4e8f-99b3-9ca87c01d643" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/ALLOWANCEFORCREDITLOSSESScheduleofAllowanceforCreditLossesbyLoanSegmentDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#ALLOWANCEFORCREDITLOSSESScheduleofAllowanceforCreditLossesbyLoanSegmentDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/ALLOWANCEFORCREDITLOSSESScheduleofAllowanceforCreditLossesbyLoanSegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_adccf717-7f20-4fdd-badd-064336533567" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_f2a7d60a-9077-41c6-9ca1-efa0bb441476" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_adccf717-7f20-4fdd-badd-064336533567" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_f2a7d60a-9077-41c6-9ca1-efa0bb441476" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_0f0ea32b-b9a0-429a-8529-ee7cbcba5281" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_f2a7d60a-9077-41c6-9ca1-efa0bb441476" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_0f0ea32b-b9a0-429a-8529-ee7cbcba5281" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0f0ea32b-b9a0-429a-8529-ee7cbcba5281_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_0f0ea32b-b9a0-429a-8529-ee7cbcba5281" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0f0ea32b-b9a0-429a-8529-ee7cbcba5281_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8f9c9669-878e-49a6-9d1a-1bc6ff4154a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_0f0ea32b-b9a0-429a-8529-ee7cbcba5281" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8f9c9669-878e-49a6-9d1a-1bc6ff4154a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ResidentialRealEstateSegmentMember_c736ff9c-fa46-403d-ad45-a7eaece6e5c7" xlink:href="bafn-20251231.xsd#bafn_ResidentialRealEstateSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8f9c9669-878e-49a6-9d1a-1bc6ff4154a4" xlink:to="loc_bafn_ResidentialRealEstateSegmentMember_c736ff9c-fa46-403d-ad45-a7eaece6e5c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_32386356-61d4-414f-864e-5f2589c240a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8f9c9669-878e-49a6-9d1a-1bc6ff4154a4" xlink:to="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_32386356-61d4-414f-864e-5f2589c240a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConstructionAndLandRealEstateSegmentMember_bbf0c62a-fe96-4215-bb1e-e64b836ab2b2" xlink:href="bafn-20251231.xsd#bafn_ConstructionAndLandRealEstateSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8f9c9669-878e-49a6-9d1a-1bc6ff4154a4" xlink:to="loc_bafn_ConstructionAndLandRealEstateSegmentMember_bbf0c62a-fe96-4215-bb1e-e64b836ab2b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_CommercialAndIndustrialSegmentMember_6d62f051-7314-4b97-b849-3274c5997317" xlink:href="bafn-20251231.xsd#bafn_CommercialAndIndustrialSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8f9c9669-878e-49a6-9d1a-1bc6ff4154a4" xlink:to="loc_bafn_CommercialAndIndustrialSegmentMember_6d62f051-7314-4b97-b849-3274c5997317" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_CommercialAndIndustrialPPPSegmentMember_6600a909-6f5c-4eef-a0d1-7899dead91c8" xlink:href="bafn-20251231.xsd#bafn_CommercialAndIndustrialPPPSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8f9c9669-878e-49a6-9d1a-1bc6ff4154a4" xlink:to="loc_bafn_CommercialAndIndustrialPPPSegmentMember_6600a909-6f5c-4eef-a0d1-7899dead91c8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConsumerAndOtherSegmentMember_e96a875a-7c16-4180-8298-91305e5a8269" xlink:href="bafn-20251231.xsd#bafn_ConsumerAndOtherSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8f9c9669-878e-49a6-9d1a-1bc6ff4154a4" xlink:to="loc_bafn_ConsumerAndOtherSegmentMember_e96a875a-7c16-4180-8298-91305e5a8269" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward_ed28b9e0-b7af-480d-9696-b64f6161744d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_adccf717-7f20-4fdd-badd-064336533567" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward_ed28b9e0-b7af-480d-9696-b64f6161744d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_a1af7a1b-e60c-488c-a4c5-4fcf0400ad40" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward_ed28b9e0-b7af-480d-9696-b64f6161744d" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_a1af7a1b-e60c-488c-a4c5-4fcf0400ad40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossChargeOffs_4e9ad574-c9a3-40a6-99cd-f3cd90906a09" xlink:href="bafn-20251231.xsd#bafn_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossChargeOffs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward_ed28b9e0-b7af-480d-9696-b64f6161744d" xlink:to="loc_bafn_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossChargeOffs_4e9ad574-c9a3-40a6-99cd-f3cd90906a09" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery_ae7849a5-1ba1-44cf-9d1c-8a726a96ea61" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward_ed28b9e0-b7af-480d-9696-b64f6161744d" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery_ae7849a5-1ba1-44cf-9d1c-8a726a96ea61" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal_531ca7b8-49dc-4422-8756-03c785b682be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRollForward_ed28b9e0-b7af-480d-9696-b64f6161744d" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal_531ca7b8-49dc-4422-8756-03c785b682be" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_25192213-58b5-43b7-9487-3e83a4fb3809" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/ALLOWANCEFORCREDITLOSSESScheduleofRecordedInvestmentinNonaccrualandLoansPastDueover89DaysStillonAccrualbyLoanSegmentDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#ALLOWANCEFORCREDITLOSSESScheduleofRecordedInvestmentinNonaccrualandLoansPastDueover89DaysStillonAccrualbyLoanSegmentDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/ALLOWANCEFORCREDITLOSSESScheduleofRecordedInvestmentinNonaccrualandLoansPastDueover89DaysStillonAccrualbyLoanSegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableNonaccrualStatusLineItems_49dde36c-823d-4dd6-9527-fb3b807fefcd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableNonaccrualStatusLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableNonaccrualTable_97bc353d-358b-49d9-b6fa-6e46d38bdf3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableNonaccrualTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableNonaccrualStatusLineItems_49dde36c-823d-4dd6-9527-fb3b807fefcd" xlink:to="loc_us-gaap_FinancingReceivableNonaccrualTable_97bc353d-358b-49d9-b6fa-6e46d38bdf3f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_b2d754e3-dede-4856-90e0-bcb0ca67e17e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FinancingReceivableNonaccrualTable_97bc353d-358b-49d9-b6fa-6e46d38bdf3f" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_b2d754e3-dede-4856-90e0-bcb0ca67e17e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_b2d754e3-dede-4856-90e0-bcb0ca67e17e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_b2d754e3-dede-4856-90e0-bcb0ca67e17e" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_b2d754e3-dede-4856-90e0-bcb0ca67e17e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_3bf63400-7d41-43a5-a59f-9b79f82f74eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_b2d754e3-dede-4856-90e0-bcb0ca67e17e" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_3bf63400-7d41-43a5-a59f-9b79f82f74eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ResidentialRealEstateSegmentMember_336b78e5-7ed2-4187-95df-0d1e480b1735" xlink:href="bafn-20251231.xsd#bafn_ResidentialRealEstateSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_3bf63400-7d41-43a5-a59f-9b79f82f74eb" xlink:to="loc_bafn_ResidentialRealEstateSegmentMember_336b78e5-7ed2-4187-95df-0d1e480b1735" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_03db1fda-950e-48b4-bdf9-2ec9f34e09ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_3bf63400-7d41-43a5-a59f-9b79f82f74eb" xlink:to="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_03db1fda-950e-48b4-bdf9-2ec9f34e09ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConstructionAndLandRealEstateSegmentMember_fddf7277-c3eb-4ba7-93c9-455c41bd4d16" xlink:href="bafn-20251231.xsd#bafn_ConstructionAndLandRealEstateSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_3bf63400-7d41-43a5-a59f-9b79f82f74eb" xlink:to="loc_bafn_ConstructionAndLandRealEstateSegmentMember_fddf7277-c3eb-4ba7-93c9-455c41bd4d16" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_CommercialAndIndustrialSegmentMember_3e44b57e-30de-424c-95f8-ebbea5268e39" xlink:href="bafn-20251231.xsd#bafn_CommercialAndIndustrialSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_3bf63400-7d41-43a5-a59f-9b79f82f74eb" xlink:to="loc_bafn_CommercialAndIndustrialSegmentMember_3e44b57e-30de-424c-95f8-ebbea5268e39" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConsumerAndOtherSegmentMember_688b0e77-64dc-419b-94c8-cc89b57507a0" xlink:href="bafn-20251231.xsd#bafn_ConsumerAndOtherSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_3bf63400-7d41-43a5-a59f-9b79f82f74eb" xlink:to="loc_bafn_ConsumerAndOtherSegmentMember_688b0e77-64dc-419b-94c8-cc89b57507a0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance_0bb74039-fe55-43b4-a60d-25e5708f202c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableNonaccrualStatusLineItems_49dde36c-823d-4dd6-9527-fb3b807fefcd" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance_0bb74039-fe55-43b4-a60d-25e5708f202c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual_0bf4a81b-fb18-4009-9132-ef115d202589" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableNonaccrualStatusLineItems_49dde36c-823d-4dd6-9527-fb3b807fefcd" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual_0bf4a81b-fb18-4009-9132-ef115d202589" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing_16b17845-f430-4f2a-83e7-6aaa38e04a42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableNonaccrualStatusLineItems_49dde36c-823d-4dd6-9527-fb3b807fefcd" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing_16b17845-f430-4f2a-83e7-6aaa38e04a42" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/ALLOWANCEFORCREDITLOSSESScheduleofAmortizedCostBasisofIndividuallyAnalyzedCollateralDependentLoansDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#ALLOWANCEFORCREDITLOSSESScheduleofAmortizedCostBasisofIndividuallyAnalyzedCollateralDependentLoansDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/ALLOWANCEFORCREDITLOSSESScheduleofAmortizedCostBasisofIndividuallyAnalyzedCollateralDependentLoansDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_5a93aa31-d580-41e0-8c47-ee150eee62ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_5318814d-9a46-4118-aa11-c3b96dd36f3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_5a93aa31-d580-41e0-8c47-ee150eee62ff" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_5318814d-9a46-4118-aa11-c3b96dd36f3f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_c210b1ee-3906-4c69-9286-51e8d1cbf992" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_5318814d-9a46-4118-aa11-c3b96dd36f3f" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_c210b1ee-3906-4c69-9286-51e8d1cbf992" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_c210b1ee-3906-4c69-9286-51e8d1cbf992_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_c210b1ee-3906-4c69-9286-51e8d1cbf992" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_c210b1ee-3906-4c69-9286-51e8d1cbf992_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_cfc42763-5e86-498b-aef1-6518923f912e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_c210b1ee-3906-4c69-9286-51e8d1cbf992" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_cfc42763-5e86-498b-aef1-6518923f912e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_1d827bae-6192-446c-b2e7-a66a60b14822" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_cfc42763-5e86-498b-aef1-6518923f912e" xlink:to="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_1d827bae-6192-446c-b2e7-a66a60b14822" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralAxis_b94727f6-122c-4f14-bca2-ecbdd16fdf71" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_5318814d-9a46-4118-aa11-c3b96dd36f3f" xlink:to="loc_us-gaap_CollateralAxis_b94727f6-122c-4f14-bca2-ecbdd16fdf71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralDomain_b94727f6-122c-4f14-bca2-ecbdd16fdf71_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CollateralAxis_b94727f6-122c-4f14-bca2-ecbdd16fdf71" xlink:to="loc_us-gaap_CollateralDomain_b94727f6-122c-4f14-bca2-ecbdd16fdf71_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralDomain_67441611-7549-4856-99cb-33266d4bbac5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CollateralAxis_b94727f6-122c-4f14-bca2-ecbdd16fdf71" xlink:to="loc_us-gaap_CollateralDomain_67441611-7549-4856-99cb-33266d4bbac5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateMember_d1ad6ba1-efab-458a-b275-6909c5d1edfd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollateralDomain_67441611-7549-4856-99cb-33266d4bbac5" xlink:to="loc_us-gaap_RealEstateMember_d1ad6ba1-efab-458a-b275-6909c5d1edfd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_4dc2b04f-793d-49e0-beca-854b92c324c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_5a93aa31-d580-41e0-8c47-ee150eee62ff" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_4dc2b04f-793d-49e0-beca-854b92c324c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_37f1610a-47e2-4a8b-bb7d-93d22d5e882c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_5a93aa31-d580-41e0-8c47-ee150eee62ff" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_37f1610a-47e2-4a8b-bb7d-93d22d5e882c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/ALLOWANCEFORCREDITLOSSESScheduleofAgingofRecordedInvestmentinPastDueGrossLoansatAmortizedCostDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#ALLOWANCEFORCREDITLOSSESScheduleofAgingofRecordedInvestmentinPastDueGrossLoansatAmortizedCostDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/ALLOWANCEFORCREDITLOSSESScheduleofAgingofRecordedInvestmentinPastDueGrossLoansatAmortizedCostDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_22f2164e-bcf1-4c4c-b177-679d33376f49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_9ba43f7d-9a4c-4067-b9a3-4f9ca514dddb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFinancingReceivablesPastDueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_22f2164e-bcf1-4c4c-b177-679d33376f49" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_9ba43f7d-9a4c-4067-b9a3-4f9ca514dddb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_0aa04d8c-5018-4efa-9375-0c1614f58f61" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_9ba43f7d-9a4c-4067-b9a3-4f9ca514dddb" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_0aa04d8c-5018-4efa-9375-0c1614f58f61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0aa04d8c-5018-4efa-9375-0c1614f58f61_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_0aa04d8c-5018-4efa-9375-0c1614f58f61" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0aa04d8c-5018-4efa-9375-0c1614f58f61_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_5ddbed06-2018-4758-b02b-ae640e98576b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_0aa04d8c-5018-4efa-9375-0c1614f58f61" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_5ddbed06-2018-4758-b02b-ae640e98576b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ResidentialRealEstateSegmentMember_95f4720b-759a-4e27-be65-d4943bc4d4f0" xlink:href="bafn-20251231.xsd#bafn_ResidentialRealEstateSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_5ddbed06-2018-4758-b02b-ae640e98576b" xlink:to="loc_bafn_ResidentialRealEstateSegmentMember_95f4720b-759a-4e27-be65-d4943bc4d4f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_84ba03bb-265a-4e3a-bd14-001dd0544c6f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_5ddbed06-2018-4758-b02b-ae640e98576b" xlink:to="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_84ba03bb-265a-4e3a-bd14-001dd0544c6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConstructionAndLandRealEstateSegmentMember_b67edc71-ebc0-4c85-96ef-51faf853a7b6" xlink:href="bafn-20251231.xsd#bafn_ConstructionAndLandRealEstateSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_5ddbed06-2018-4758-b02b-ae640e98576b" xlink:to="loc_bafn_ConstructionAndLandRealEstateSegmentMember_b67edc71-ebc0-4c85-96ef-51faf853a7b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_CommercialAndIndustrialSegmentMember_a8869cf3-b801-4263-9f99-d70d2c614f11" xlink:href="bafn-20251231.xsd#bafn_CommercialAndIndustrialSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_5ddbed06-2018-4758-b02b-ae640e98576b" xlink:to="loc_bafn_CommercialAndIndustrialSegmentMember_a8869cf3-b801-4263-9f99-d70d2c614f11" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_CommercialAndIndustrialPPPSegmentMember_83bedb73-feef-47ec-84c4-71576f735b45" xlink:href="bafn-20251231.xsd#bafn_CommercialAndIndustrialPPPSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_5ddbed06-2018-4758-b02b-ae640e98576b" xlink:to="loc_bafn_CommercialAndIndustrialPPPSegmentMember_83bedb73-feef-47ec-84c4-71576f735b45" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConsumerAndOtherSegmentMember_7b5b0705-7fa9-44cc-8f02-fd654492d0b0" xlink:href="bafn-20251231.xsd#bafn_ConsumerAndOtherSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_5ddbed06-2018-4758-b02b-ae640e98576b" xlink:to="loc_bafn_ConsumerAndOtherSegmentMember_7b5b0705-7fa9-44cc-8f02-fd654492d0b0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_PPPLoanDelinquenciesMember_81f9f824-857e-4ce9-8cfa-742a7d207669" xlink:href="bafn-20251231.xsd#bafn_PPPLoanDelinquenciesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_5ddbed06-2018-4758-b02b-ae640e98576b" xlink:to="loc_bafn_PPPLoanDelinquenciesMember_81f9f824-857e-4ce9-8cfa-742a7d207669" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_e3bc256f-dbe5-467f-9d17-6c007bb19ee9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablesPeriodPastDueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_9ba43f7d-9a4c-4067-b9a3-4f9ca514dddb" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_e3bc256f-dbe5-467f-9d17-6c007bb19ee9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_e3bc256f-dbe5-467f-9d17-6c007bb19ee9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_e3bc256f-dbe5-467f-9d17-6c007bb19ee9" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_e3bc256f-dbe5-467f-9d17-6c007bb19ee9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_6fd49a86-5d22-49a4-af7a-529ceb9be3e5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_e3bc256f-dbe5-467f-9d17-6c007bb19ee9" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_6fd49a86-5d22-49a4-af7a-529ceb9be3e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialAssetPastDueMember_dfcd00b2-1f35-4b49-95b4-b24576cecca5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialAssetPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_6fd49a86-5d22-49a4-af7a-529ceb9be3e5" xlink:to="loc_us-gaap_FinancialAssetPastDueMember_dfcd00b2-1f35-4b49-95b4-b24576cecca5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_FinancialAsset30To89DaysPastDueMember_873b17b0-33b1-4604-b5fa-564930cc8f9f" xlink:href="bafn-20251231.xsd#bafn_FinancialAsset30To89DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialAssetPastDueMember_dfcd00b2-1f35-4b49-95b4-b24576cecca5" xlink:to="loc_bafn_FinancialAsset30To89DaysPastDueMember_873b17b0-33b1-4604-b5fa-564930cc8f9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember_8d57949d-907a-445c-950f-3c7250ffc9a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialAssetPastDueMember_dfcd00b2-1f35-4b49-95b4-b24576cecca5" xlink:to="loc_us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember_8d57949d-907a-445c-950f-3c7250ffc9a4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialAssetNotPastDueMember_05c1408c-6938-426e-a3d6-a67e8997d97f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialAssetNotPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_6fd49a86-5d22-49a4-af7a-529ceb9be3e5" xlink:to="loc_us-gaap_FinancialAssetNotPastDueMember_05c1408c-6938-426e-a3d6-a67e8997d97f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess_974e4c26-6fdd-4f18-9a4b-91cbb318bd20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_22f2164e-bcf1-4c4c-b177-679d33376f49" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess_974e4c26-6fdd-4f18-9a4b-91cbb318bd20" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossGuaranteedBalance_7ceae428-2bfa-48b8-a0e0-6bb2d10ad86d" xlink:href="bafn-20251231.xsd#bafn_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossGuaranteedBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_22f2164e-bcf1-4c4c-b177-679d33376f49" xlink:to="loc_bafn_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossGuaranteedBalance_7ceae428-2bfa-48b8-a0e0-6bb2d10ad86d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetailLandSalesDelinquentAccountsReceivable_fdc5d330-b2e8-46e3-96ae-f85e1480b8c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetailLandSalesDelinquentAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_22f2164e-bcf1-4c4c-b177-679d33376f49" xlink:to="loc_us-gaap_RetailLandSalesDelinquentAccountsReceivable_fdc5d330-b2e8-46e3-96ae-f85e1480b8c6" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/ALLOWANCEFORCREDITLOSSESScheduleofCreditExposurefortheLoanPortfolioDisaggregatedbyLoanSegmentDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#ALLOWANCEFORCREDITLOSSESScheduleofCreditExposurefortheLoanPortfolioDisaggregatedbyLoanSegmentDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/ALLOWANCEFORCREDITLOSSESScheduleofCreditExposurefortheLoanPortfolioDisaggregatedbyLoanSegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_3897e23c-0b51-4a3d-aa94-81af80d633c1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableRecordedInvestmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_d18c3400-f773-4398-a943-5cb4da1493e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_3897e23c-0b51-4a3d-aa94-81af80d633c1" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_d18c3400-f773-4398-a943-5cb4da1493e9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_265910f4-0af7-45f7-b2de-62a2c4bc4916" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_d18c3400-f773-4398-a943-5cb4da1493e9" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_265910f4-0af7-45f7-b2de-62a2c4bc4916" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_265910f4-0af7-45f7-b2de-62a2c4bc4916_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_265910f4-0af7-45f7-b2de-62a2c4bc4916" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_265910f4-0af7-45f7-b2de-62a2c4bc4916_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_900d1881-28b0-4fd1-9910-53fd033ea633" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_265910f4-0af7-45f7-b2de-62a2c4bc4916" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_900d1881-28b0-4fd1-9910-53fd033ea633" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_22e0235c-384b-4b47-ac3c-f91283ec55c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_900d1881-28b0-4fd1-9910-53fd033ea633" xlink:to="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_22e0235c-384b-4b47-ac3c-f91283ec55c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConstructionAndLandRealEstateSegmentMember_51e919f2-e039-4a95-82c5-d6093d7dac3a" xlink:href="bafn-20251231.xsd#bafn_ConstructionAndLandRealEstateSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_900d1881-28b0-4fd1-9910-53fd033ea633" xlink:to="loc_bafn_ConstructionAndLandRealEstateSegmentMember_51e919f2-e039-4a95-82c5-d6093d7dac3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_CommercialAndIndustrialSegmentMember_222afc36-df10-4d8f-894a-2948dd66e6bf" xlink:href="bafn-20251231.xsd#bafn_CommercialAndIndustrialSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_900d1881-28b0-4fd1-9910-53fd033ea633" xlink:to="loc_bafn_CommercialAndIndustrialSegmentMember_222afc36-df10-4d8f-894a-2948dd66e6bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_CommercialAndIndustrialPPPSegmentMember_1827c5bb-f1aa-49bc-bedc-704162253c84" xlink:href="bafn-20251231.xsd#bafn_CommercialAndIndustrialPPPSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_900d1881-28b0-4fd1-9910-53fd033ea633" xlink:to="loc_bafn_CommercialAndIndustrialPPPSegmentMember_1827c5bb-f1aa-49bc-bedc-704162253c84" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ResidentialRealEstateSegmentMember_ebea2b9c-93e3-47d3-a84b-ce03dc825d01" xlink:href="bafn-20251231.xsd#bafn_ResidentialRealEstateSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_900d1881-28b0-4fd1-9910-53fd033ea633" xlink:to="loc_bafn_ResidentialRealEstateSegmentMember_ebea2b9c-93e3-47d3-a84b-ce03dc825d01" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConsumerAndOtherSegmentMember_96ee0d63-c195-4cf9-aebd-47159227c1c6" xlink:href="bafn-20251231.xsd#bafn_ConsumerAndOtherSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_900d1881-28b0-4fd1-9910-53fd033ea633" xlink:to="loc_bafn_ConsumerAndOtherSegmentMember_96ee0d63-c195-4cf9-aebd-47159227c1c6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentAxis_58bc87ad-4126-4c82-8482-a7808f987f64" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InternalCreditAssessmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_d18c3400-f773-4398-a943-5cb4da1493e9" xlink:to="loc_us-gaap_InternalCreditAssessmentAxis_58bc87ad-4126-4c82-8482-a7808f987f64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentDomain_58bc87ad-4126-4c82-8482-a7808f987f64_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InternalCreditAssessmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InternalCreditAssessmentAxis_58bc87ad-4126-4c82-8482-a7808f987f64" xlink:to="loc_us-gaap_InternalCreditAssessmentDomain_58bc87ad-4126-4c82-8482-a7808f987f64_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentDomain_5e1e5e78-a638-406b-83a1-a87dbbdc3aee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InternalCreditAssessmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InternalCreditAssessmentAxis_58bc87ad-4126-4c82-8482-a7808f987f64" xlink:to="loc_us-gaap_InternalCreditAssessmentDomain_5e1e5e78-a638-406b-83a1-a87dbbdc3aee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PassMember_e7098859-ddf1-4104-8a1e-5606c37e741e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PassMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_5e1e5e78-a638-406b-83a1-a87dbbdc3aee" xlink:to="loc_us-gaap_PassMember_e7098859-ddf1-4104-8a1e-5606c37e741e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SpecialMentionMember_0cef7a9b-ccdf-42c3-8ffa-de032970c79d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SpecialMentionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_5e1e5e78-a638-406b-83a1-a87dbbdc3aee" xlink:to="loc_us-gaap_SpecialMentionMember_0cef7a9b-ccdf-42c3-8ffa-de032970c79d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubstandardMember_aa3e154e-6921-4e34-b682-1284bbae3425" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubstandardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_5e1e5e78-a638-406b-83a1-a87dbbdc3aee" xlink:to="loc_us-gaap_SubstandardMember_aa3e154e-6921-4e34-b682-1284bbae3425" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DoubtfulMember_c87d8e7f-d647-47ec-be65-4f6a39353e8a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DoubtfulMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_5e1e5e78-a638-406b-83a1-a87dbbdc3aee" xlink:to="loc_us-gaap_DoubtfulMember_c87d8e7f-d647-47ec-be65-4f6a39353e8a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract_8af785ce-dd9b-4958-8676-16e5436e65d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_3897e23c-0b51-4a3d-aa94-81af80d633c1" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract_8af785ce-dd9b-4958-8676-16e5436e65d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear_f75e1913-6b4d-4618-a2c6-221fab9250ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract_8af785ce-dd9b-4958-8676-16e5436e65d9" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear_f75e1913-6b4d-4618-a2c6-221fab9250ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear_37c214e7-b780-40dc-85f5-282be1ab6a7a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract_8af785ce-dd9b-4958-8676-16e5436e65d9" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear_37c214e7-b780-40dc-85f5-282be1ab6a7a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear_022c627f-73d5-4bfa-9dff-b18b7b94afe5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract_8af785ce-dd9b-4958-8676-16e5436e65d9" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear_022c627f-73d5-4bfa-9dff-b18b7b94afe5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear_961ebd5a-cf39-4e31-b801-e44f7aaeafef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract_8af785ce-dd9b-4958-8676-16e5436e65d9" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear_961ebd5a-cf39-4e31-b801-e44f7aaeafef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear_9ee1b57b-ea82-4780-a5b0-36110df57152" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract_8af785ce-dd9b-4958-8676-16e5436e65d9" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear_9ee1b57b-ea82-4780-a5b0-36110df57152" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear_8137b65b-baa1-423d-abd1-a891597d8205" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract_8af785ce-dd9b-4958-8676-16e5436e65d9" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear_8137b65b-baa1-423d-abd1-a891597d8205" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolving_347190b5-5005-4bcc-af90-fb8f757532bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolving"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract_8af785ce-dd9b-4958-8676-16e5436e65d9" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolving_347190b5-5005-4bcc-af90-fb8f757532bb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan_c4817e7f-e8d8-406a-bb0f-a0b9b8006177" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract_8af785ce-dd9b-4958-8676-16e5436e65d9" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan_c4817e7f-e8d8-406a-bb0f-a0b9b8006177" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_a687ef4f-7778-49d3-9a63-2a055be4b57d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossByOriginationYearAbstract_8af785ce-dd9b-4958-8676-16e5436e65d9" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_a687ef4f-7778-49d3-9a63-2a055be4b57d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_3897e23c-0b51-4a3d-aa94-81af80d633c1" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff_6de7e271-70c8-45fb-b546-f531c2f7ae51" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff_6de7e271-70c8-45fb-b546-f531c2f7ae51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff_12adc8e8-b143-47cc-a230-d1833a8449d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff_12adc8e8-b143-47cc-a230-d1833a8449d1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff_b83bfa9e-27f7-4e52-9d2a-af8d926c23c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff_b83bfa9e-27f7-4e52-9d2a-af8d926c23c2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff_3c461f45-d268-45f0-adc2-16f5f2dc7f30" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff_3c461f45-d268-45f0-adc2-16f5f2dc7f30" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff_bd5fc2f9-0339-44b9-bc74-7a0bd67ce3ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff_bd5fc2f9-0339-44b9-bc74-7a0bd67ce3ec" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff_39bead2d-17a5-4e46-bce8-41c418f8bc9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff_39bead2d-17a5-4e46-bce8-41c418f8bc9c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFourYearsBeforeCurrentFiscalYearWriteoff_54ecf588-d064-442f-b41d-b87a0503e709" xlink:href="bafn-20251231.xsd#bafn_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFourYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:to="loc_bafn_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFourYearsBeforeCurrentFiscalYearWriteoff_54ecf588-d064-442f-b41d-b87a0503e709" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff_e851628a-179c-4255-8db6-43ba7da49719" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff_e851628a-179c-4255-8db6-43ba7da49719" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff_cb04d23f-6bbb-48f6-b3c3-a36e80aa3781" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff_cb04d23f-6bbb-48f6-b3c3-a36e80aa3781" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_dcdfe654-2a32-42ed-8e72-ded4f2e39f0b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract_94e24953-8238-4dd8-8238-f8fc5b00940e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_dcdfe654-2a32-42ed-8e72-ded4f2e39f0b" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#FAIRVALUEScheduleofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_1a8024b4-db93-4ea1-a3eb-6c1c5a9ec673" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_f3e85a7a-a07c-406a-817c-304dd9d6d50b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_1a8024b4-db93-4ea1-a3eb-6c1c5a9ec673" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_f3e85a7a-a07c-406a-817c-304dd9d6d50b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5c96bc17-8b15-4b0a-9992-a841f546b041" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_f3e85a7a-a07c-406a-817c-304dd9d6d50b" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5c96bc17-8b15-4b0a-9992-a841f546b041" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5c96bc17-8b15-4b0a-9992-a841f546b041_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5c96bc17-8b15-4b0a-9992-a841f546b041" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5c96bc17-8b15-4b0a-9992-a841f546b041_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_659ae985-f1c4-40e5-80c5-077972016da0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5c96bc17-8b15-4b0a-9992-a841f546b041" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_659ae985-f1c4-40e5-80c5-077972016da0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_619e98a4-78ad-4898-a913-8b497af97ce9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_659ae985-f1c4-40e5-80c5-077972016da0" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_619e98a4-78ad-4898-a913-8b497af97ce9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_19d8c107-93ff-4aba-9fdf-965d8df9a133" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_659ae985-f1c4-40e5-80c5-077972016da0" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_19d8c107-93ff-4aba-9fdf-965d8df9a133" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_2923873c-fada-4905-b595-bf015f4a0a66" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_659ae985-f1c4-40e5-80c5-077972016da0" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_2923873c-fada-4905-b595-bf015f4a0a66" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_93eea863-7397-4720-a82a-71b086a65c89" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_f3e85a7a-a07c-406a-817c-304dd9d6d50b" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_93eea863-7397-4720-a82a-71b086a65c89" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_93eea863-7397-4720-a82a-71b086a65c89_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_93eea863-7397-4720-a82a-71b086a65c89" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_93eea863-7397-4720-a82a-71b086a65c89_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_3ae8c831-c1fd-4ca6-b6dd-446a84caf885" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_93eea863-7397-4720-a82a-71b086a65c89" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_3ae8c831-c1fd-4ca6-b6dd-446a84caf885" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_f340c49d-cb7c-45f6-93ad-54f49d7b0866" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_3ae8c831-c1fd-4ca6-b6dd-446a84caf885" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_f340c49d-cb7c-45f6-93ad-54f49d7b0866" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_9816857f-3421-4d32-8c6a-420006186c9d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_1a8024b4-db93-4ea1-a3eb-6c1c5a9ec673" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_9816857f-3421-4d32-8c6a-420006186c9d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_1184047e-258a-452b-8a2a-39c70958b473" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_9816857f-3421-4d32-8c6a-420006186c9d" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_1184047e-258a-452b-8a2a-39c70958b473" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableFairValueDisclosure_6aef3614-5100-490c-b45c-9daa4771de83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LoansReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_9816857f-3421-4d32-8c6a-420006186c9d" xlink:to="loc_us-gaap_LoansReceivableFairValueDisclosure_6aef3614-5100-490c-b45c-9daa4771de83" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofFairValueCarryingAmountandtheUnpaidPrincipalOutstandingofHFIGovernmentGuaranteedLoansDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#FAIRVALUEScheduleofFairValueCarryingAmountandtheUnpaidPrincipalOutstandingofHFIGovernmentGuaranteedLoansDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofFairValueCarryingAmountandtheUnpaidPrincipalOutstandingofHFIGovernmentGuaranteedLoansDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_d09ad884-19f4-4306-bff4-1d7d83394d1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionQuantitativeDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_6eb8d41e-6361-47d1-8243-29bc60762e0c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionQuantitativeDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_d09ad884-19f4-4306-bff4-1d7d83394d1a" xlink:to="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_6eb8d41e-6361-47d1-8243-29bc60762e0c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_2452652a-7afe-4d44-8376-92674fab4771" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_6eb8d41e-6361-47d1-8243-29bc60762e0c" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_2452652a-7afe-4d44-8376-92674fab4771" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_2452652a-7afe-4d44-8376-92674fab4771_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_2452652a-7afe-4d44-8376-92674fab4771" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_2452652a-7afe-4d44-8376-92674fab4771_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_d1536801-c715-4866-b165-9563188504ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_2452652a-7afe-4d44-8376-92674fab4771" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_d1536801-c715-4866-b165-9563188504ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_8a05b22a-17dd-4ddb-8192-14e2bf428005" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialRealEstatePortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_d1536801-c715-4866-b165-9563188504ea" xlink:to="loc_us-gaap_CommercialRealEstatePortfolioSegmentMember_8a05b22a-17dd-4ddb-8192-14e2bf428005" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_CommercialAndIndustrialSegmentMember_48e339c3-3148-417e-abff-dd247c2c73a5" xlink:href="bafn-20251231.xsd#bafn_CommercialAndIndustrialSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_d1536801-c715-4866-b165-9563188504ea" xlink:to="loc_bafn_CommercialAndIndustrialSegmentMember_48e339c3-3148-417e-abff-dd247c2c73a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_FairValueOptionLoansHeldAsAssetsFairValue_f9bf9989-8a6e-463c-a3f4-da251a585a0c" xlink:href="bafn-20251231.xsd#bafn_FairValueOptionLoansHeldAsAssetsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_d09ad884-19f4-4306-bff4-1d7d83394d1a" xlink:to="loc_bafn_FairValueOptionLoansHeldAsAssetsFairValue_f9bf9989-8a6e-463c-a3f4-da251a585a0c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_FairValueOptionLoansHeldAsAssetsUnpaidPrincipalBalance_0ab124a9-dbec-4148-82f1-ab5be7555f90" xlink:href="bafn-20251231.xsd#bafn_FairValueOptionLoansHeldAsAssetsUnpaidPrincipalBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_d09ad884-19f4-4306-bff4-1d7d83394d1a" xlink:to="loc_bafn_FairValueOptionLoansHeldAsAssetsUnpaidPrincipalBalance_0ab124a9-dbec-4148-82f1-ab5be7555f90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOptionLoansHeldAsAssetsAggregateDifference_d3bca425-60f0-40e6-a65f-73ddebf9b99b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionLoansHeldAsAssetsAggregateDifference"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_d09ad884-19f4-4306-bff4-1d7d83394d1a" xlink:to="loc_us-gaap_FairValueOptionLoansHeldAsAssetsAggregateDifference_d3bca425-60f0-40e6-a65f-73ddebf9b99b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus_0555c870-47d2-4abd-8dc0-f87b97cb2fe2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_d09ad884-19f4-4306-bff4-1d7d83394d1a" xlink:to="loc_us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus_0555c870-47d2-4abd-8dc0-f87b97cb2fe2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatusUnpaidPrincipalBalance_c548e632-c4a6-46c7-a9e0-a3cd356be820" xlink:href="bafn-20251231.xsd#bafn_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatusUnpaidPrincipalBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_d09ad884-19f4-4306-bff4-1d7d83394d1a" xlink:to="loc_bafn_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatusUnpaidPrincipalBalance_c548e632-c4a6-46c7-a9e0-a3cd356be820" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatusAggregatedDifference_eeedbfd0-7e63-4831-b48c-e7ebdcfe2def" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatusAggregatedDifference"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_d09ad884-19f4-4306-bff4-1d7d83394d1a" xlink:to="loc_us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatusAggregatedDifference_eeedbfd0-7e63-4831-b48c-e7ebdcfe2def" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOptionLoansHeldAsAssets90DaysOrMorePastDue_e071e982-74af-462b-aa61-7b93524f4fc4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionLoansHeldAsAssets90DaysOrMorePastDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_d09ad884-19f4-4306-bff4-1d7d83394d1a" xlink:to="loc_us-gaap_FairValueOptionLoansHeldAsAssets90DaysOrMorePastDue_e071e982-74af-462b-aa61-7b93524f4fc4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_FairValueOptionLoansHeldAsAssets90DaysOrMorePastDueUnpaidPrincipalBalance_e9be5b57-e385-43ce-aed2-2791d3b0fa41" xlink:href="bafn-20251231.xsd#bafn_FairValueOptionLoansHeldAsAssets90DaysOrMorePastDueUnpaidPrincipalBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_d09ad884-19f4-4306-bff4-1d7d83394d1a" xlink:to="loc_bafn_FairValueOptionLoansHeldAsAssets90DaysOrMorePastDueUnpaidPrincipalBalance_e9be5b57-e385-43ce-aed2-2791d3b0fa41" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOptionLoansHeldAsAssets90DaysOrMorePastDueAggregateDifference_770aba1b-b337-4a6d-b9e8-0e277701c8d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionLoansHeldAsAssets90DaysOrMorePastDueAggregateDifference"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_d09ad884-19f4-4306-bff4-1d7d83394d1a" xlink:to="loc_us-gaap_FairValueOptionLoansHeldAsAssets90DaysOrMorePastDueAggregateDifference_770aba1b-b337-4a6d-b9e8-0e277701c8d8" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofGainsandLossesfromChangesinFairValueandInterestIncomeIncludedinEarningsDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#FAIRVALUEScheduleofGainsandLossesfromChangesinFairValueandInterestIncomeIncludedinEarningsDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofGainsandLossesfromChangesinFairValueandInterestIncomeIncludedinEarningsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_015866d3-46dc-4bc9-a7d9-d48f8f70a6b6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionQuantitativeDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_868e4808-43d0-42f9-84c2-446434e8eabb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionQuantitativeDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_015866d3-46dc-4bc9-a7d9-d48f8f70a6b6" xlink:to="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_868e4808-43d0-42f9-84c2-446434e8eabb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_75e46606-c68e-4e37-9cce-5f6ae8850f6a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresTable_868e4808-43d0-42f9-84c2-446434e8eabb" xlink:to="loc_us-gaap_FinancialInstrumentAxis_75e46606-c68e-4e37-9cce-5f6ae8850f6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_75e46606-c68e-4e37-9cce-5f6ae8850f6a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_75e46606-c68e-4e37-9cce-5f6ae8850f6a" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_75e46606-c68e-4e37-9cce-5f6ae8850f6a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b9bd5162-ffa9-42d6-81c0-b018ebe3aa2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_75e46606-c68e-4e37-9cce-5f6ae8850f6a" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b9bd5162-ffa9-42d6-81c0-b018ebe3aa2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_SBALoanMember_4a2412f4-767a-4cb4-bd2a-2db696f37ea1" xlink:href="bafn-20251231.xsd#bafn_SBALoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b9bd5162-ffa9-42d6-81c0-b018ebe3aa2f" xlink:to="loc_bafn_SBALoanMember_4a2412f4-767a-4cb4-bd2a-2db696f37ea1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeInterestEarningAsset_1bac6798-c6c7-4d4e-9a4a-6b5aeb4ea3ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeInterestEarningAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_015866d3-46dc-4bc9-a7d9-d48f8f70a6b6" xlink:to="loc_us-gaap_InterestIncomeInterestEarningAsset_1bac6798-c6c7-4d4e-9a4a-6b5aeb4ea3ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOptionChangesInFairValueGainLoss1_8c5e7b03-8e83-4abc-a5ce-a0794b3c751a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOptionChangesInFairValueGainLoss1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_015866d3-46dc-4bc9-a7d9-d48f8f70a6b6" xlink:to="loc_us-gaap_FairValueOptionChangesInFairValueGainLoss1_8c5e7b03-8e83-4abc-a5ce-a0794b3c751a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_InterestIncomeOperatingAndFairValueOptionChangesInFairValueGainLoss_a041dc80-6537-4374-8b9e-4e1919a4269d" xlink:href="bafn-20251231.xsd#bafn_InterestIncomeOperatingAndFairValueOptionChangesInFairValueGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_015866d3-46dc-4bc9-a7d9-d48f8f70a6b6" xlink:to="loc_bafn_InterestIncomeOperatingAndFairValueOptionChangesInFairValueGainLoss_a041dc80-6537-4374-8b9e-4e1919a4269d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofGovernmentGuaranteedLoansHFIatFairValueWhichWereValuedonaRecurringBasisandUsedSignificantUnobservableInputsDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#FAIRVALUEScheduleofGovernmentGuaranteedLoansHFIatFairValueWhichWereValuedonaRecurringBasisandUsedSignificantUnobservableInputsDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofGovernmentGuaranteedLoansHFIatFairValueWhichWereValuedonaRecurringBasisandUsedSignificantUnobservableInputsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_4e3491f5-0d9d-43ea-8702-97814b4f6e74" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_85edb052-1be3-484a-8936-c0e5f8f2d60a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_4e3491f5-0d9d-43ea-8702-97814b4f6e74" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_85edb052-1be3-484a-8936-c0e5f8f2d60a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_4473b47e-9519-4c9c-9dc9-b591d47f8fbe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_85edb052-1be3-484a-8936-c0e5f8f2d60a" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_4473b47e-9519-4c9c-9dc9-b591d47f8fbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_4473b47e-9519-4c9c-9dc9-b591d47f8fbe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_4473b47e-9519-4c9c-9dc9-b591d47f8fbe" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_4473b47e-9519-4c9c-9dc9-b591d47f8fbe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_61da6122-e714-4a58-93ed-b3ee10d1250b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_4473b47e-9519-4c9c-9dc9-b591d47f8fbe" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_61da6122-e714-4a58-93ed-b3ee10d1250b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableMember_d91c3005-b554-4591-afdd-d085f819591e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LoansReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_61da6122-e714-4a58-93ed-b3ee10d1250b" xlink:to="loc_us-gaap_LoansReceivableMember_d91c3005-b554-4591-afdd-d085f819591e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_b9cf1727-0d6b-45b7-a209-2162222dec34" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_4e3491f5-0d9d-43ea-8702-97814b4f6e74" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_b9cf1727-0d6b-45b7-a209-2162222dec34" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_2e61def6-e5c2-4235-921a-3b101767d2d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_b9cf1727-0d6b-45b7-a209-2162222dec34" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_2e61def6-e5c2-4235-921a-3b101767d2d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases_7bc14578-09cd-4f73-a0dd-c07e53534c70" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_b9cf1727-0d6b-45b7-a209-2162222dec34" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases_7bc14578-09cd-4f73-a0dd-c07e53534c70" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales_97fbb7c0-7cb8-466d-a6b9-531bbc466a90" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_b9cf1727-0d6b-45b7-a209-2162222dec34" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales_97fbb7c0-7cb8-466d-a6b9-531bbc466a90" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_b474f8c9-e9d6-4d7c-8ed9-156414701412" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_b9cf1727-0d6b-45b7-a209-2162222dec34" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_b474f8c9-e9d6-4d7c-8ed9-156414701412" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_8ac8655e-1f88-4061-b493-efc03a2b98ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_b9cf1727-0d6b-45b7-a209-2162222dec34" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_8ac8655e-1f88-4061-b493-efc03a2b98ab" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_57edc0ea-3a40-4fd6-bcb7-6d3dce6d1f0c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_b9cf1727-0d6b-45b7-a209-2162222dec34" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_57edc0ea-3a40-4fd6-bcb7-6d3dce6d1f0c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_c0ad758a-bff9-4269-9e2d-db08fac76889" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofValuationTechniqueandUnobservableInputsUsedintheValuationofGovernmentGuaranteedHFIatFairValueDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#FAIRVALUEScheduleofValuationTechniqueandUnobservableInputsUsedintheValuationofGovernmentGuaranteedHFIatFairValueDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofValuationTechniqueandUnobservableInputsUsedintheValuationofGovernmentGuaranteedHFIatFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_def5235c-c410-44d6-945d-8091cf594b6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_24fa5e6b-8e4b-4d00-8eb9-91d3059c5bfd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_def5235c-c410-44d6-945d-8091cf594b6c" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_24fa5e6b-8e4b-4d00-8eb9-91d3059c5bfd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8ab89c5a-57eb-455c-ad46-0e01765be271" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_24fa5e6b-8e4b-4d00-8eb9-91d3059c5bfd" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8ab89c5a-57eb-455c-ad46-0e01765be271" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8ab89c5a-57eb-455c-ad46-0e01765be271_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8ab89c5a-57eb-455c-ad46-0e01765be271" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8ab89c5a-57eb-455c-ad46-0e01765be271_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7a3d73fc-3b0c-47a3-b7b3-c817290d0bce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8ab89c5a-57eb-455c-ad46-0e01765be271" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7a3d73fc-3b0c-47a3-b7b3-c817290d0bce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_87a24776-33a0-418c-a803-67cfba1a5fe8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7a3d73fc-3b0c-47a3-b7b3-c817290d0bce" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_87a24776-33a0-418c-a803-67cfba1a5fe8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3609034a-548c-451d-b3b2-e02086083f49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_24fa5e6b-8e4b-4d00-8eb9-91d3059c5bfd" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3609034a-548c-451d-b3b2-e02086083f49" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_3609034a-548c-451d-b3b2-e02086083f49_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3609034a-548c-451d-b3b2-e02086083f49" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_3609034a-548c-451d-b3b2-e02086083f49_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_95961cbe-9734-4349-b0e2-f611769bd7a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3609034a-548c-451d-b3b2-e02086083f49" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_95961cbe-9734-4349-b0e2-f611769bd7a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_c0149587-a5e9-475a-95cd-de7c63607bc4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_95961cbe-9734-4349-b0e2-f611769bd7a7" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_c0149587-a5e9-475a-95cd-de7c63607bc4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_a33d7fd6-82fa-4e06-80d9-cdbf336f014a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_24fa5e6b-8e4b-4d00-8eb9-91d3059c5bfd" xlink:to="loc_srt_RangeAxis_a33d7fd6-82fa-4e06-80d9-cdbf336f014a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a33d7fd6-82fa-4e06-80d9-cdbf336f014a_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_a33d7fd6-82fa-4e06-80d9-cdbf336f014a" xlink:to="loc_srt_RangeMember_a33d7fd6-82fa-4e06-80d9-cdbf336f014a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_276f2dcd-a200-450e-bffc-0344508efe1f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_a33d7fd6-82fa-4e06-80d9-cdbf336f014a" xlink:to="loc_srt_RangeMember_276f2dcd-a200-450e-bffc-0344508efe1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_f0847916-b633-4d4e-92f2-2ef4c9472eef" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_276f2dcd-a200-450e-bffc-0344508efe1f" xlink:to="loc_srt_MinimumMember_f0847916-b633-4d4e-92f2-2ef4c9472eef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_c1513129-bc20-4ead-bdb6-c007eb4ac467" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_276f2dcd-a200-450e-bffc-0344508efe1f" xlink:to="loc_srt_MaximumMember_c1513129-bc20-4ead-bdb6-c007eb4ac467" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_c677d16d-6b47-4bab-ad83-16410d4623a7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_276f2dcd-a200-450e-bffc-0344508efe1f" xlink:to="loc_srt_WeightedAverageMember_c677d16d-6b47-4bab-ad83-16410d4623a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_8b6a45fa-44b3-45ab-949b-187ff8d702db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_24fa5e6b-8e4b-4d00-8eb9-91d3059c5bfd" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_8b6a45fa-44b3-45ab-949b-187ff8d702db" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_8b6a45fa-44b3-45ab-949b-187ff8d702db_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_8b6a45fa-44b3-45ab-949b-187ff8d702db" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_8b6a45fa-44b3-45ab-949b-187ff8d702db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_2295b3df-ba43-44b7-bffc-e2cfee9100a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_8b6a45fa-44b3-45ab-949b-187ff8d702db" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_2295b3df-ba43-44b7-bffc-e2cfee9100a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_56bdf32d-9c76-4295-8cd0-4f57d0f4f5ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_2295b3df-ba43-44b7-bffc-e2cfee9100a2" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_56bdf32d-9c76-4295-8cd0-4f57d0f4f5ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputConstantPrepaymentRateMember_c3ba13c9-1a43-42e5-ad4b-7dc5785b9ada" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputConstantPrepaymentRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_2295b3df-ba43-44b7-bffc-e2cfee9100a2" xlink:to="loc_us-gaap_MeasurementInputConstantPrepaymentRateMember_c3ba13c9-1a43-42e5-ad4b-7dc5785b9ada" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_cce5e4af-8ca1-4386-9f01-aa9af36ecef3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_24fa5e6b-8e4b-4d00-8eb9-91d3059c5bfd" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_cce5e4af-8ca1-4386-9f01-aa9af36ecef3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_cce5e4af-8ca1-4386-9f01-aa9af36ecef3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_cce5e4af-8ca1-4386-9f01-aa9af36ecef3" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_cce5e4af-8ca1-4386-9f01-aa9af36ecef3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_0a79be88-4620-42f7-961e-41259673af2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_cce5e4af-8ca1-4386-9f01-aa9af36ecef3" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_0a79be88-4620-42f7-961e-41259673af2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_GovernmentGuaranteedLoansHFIMember_9db2f6e1-c0c3-488e-9337-f9d41129021f" xlink:href="bafn-20251231.xsd#bafn_GovernmentGuaranteedLoansHFIMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_0a79be88-4620-42f7-961e-41259673af2f" xlink:to="loc_bafn_GovernmentGuaranteedLoansHFIMember_9db2f6e1-c0c3-488e-9337-f9d41129021f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableFairValueDisclosure_af10cccd-4703-4de9-be8f-5dd2584cf3a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LoansReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_def5235c-c410-44d6-945d-8091cf594b6c" xlink:to="loc_us-gaap_LoansReceivableFairValueDisclosure_af10cccd-4703-4de9-be8f-5dd2584cf3a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_LoansReceivableMeasurementInput_3f516721-a45f-423f-981d-f1f6493199ae" xlink:href="bafn-20251231.xsd#bafn_LoansReceivableMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_def5235c-c410-44d6-945d-8091cf594b6c" xlink:to="loc_bafn_LoansReceivableMeasurementInput_3f516721-a45f-423f-981d-f1f6493199ae" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofAssetsMeasuredatFairValueonaNonrecurringBasisDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#FAIRVALUEScheduleofAssetsMeasuredatFairValueonaNonrecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofAssetsMeasuredatFairValueonaNonrecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_6b3c04f2-3caf-4d4b-a447-343967785158" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_46d0e805-0a6d-47bb-823f-9407553dd285" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_6b3c04f2-3caf-4d4b-a447-343967785158" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_46d0e805-0a6d-47bb-823f-9407553dd285" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_904aca0d-c75d-4ebf-8b2c-8af40aeac53c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_46d0e805-0a6d-47bb-823f-9407553dd285" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_904aca0d-c75d-4ebf-8b2c-8af40aeac53c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_904aca0d-c75d-4ebf-8b2c-8af40aeac53c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_904aca0d-c75d-4ebf-8b2c-8af40aeac53c" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_904aca0d-c75d-4ebf-8b2c-8af40aeac53c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_c086e768-b5ca-4f46-b760-b3f1b9a22961" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_904aca0d-c75d-4ebf-8b2c-8af40aeac53c" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_c086e768-b5ca-4f46-b760-b3f1b9a22961" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsNonrecurringMember_1e307294-b149-486d-a6f3-72cd3d4fab2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsNonrecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_c086e768-b5ca-4f46-b760-b3f1b9a22961" xlink:to="loc_us-gaap_FairValueMeasurementsNonrecurringMember_1e307294-b149-486d-a6f3-72cd3d4fab2f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_dc9a98ce-5bb8-4cea-91aa-31432faf2668" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_46d0e805-0a6d-47bb-823f-9407553dd285" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_dc9a98ce-5bb8-4cea-91aa-31432faf2668" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_dc9a98ce-5bb8-4cea-91aa-31432faf2668_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_dc9a98ce-5bb8-4cea-91aa-31432faf2668" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_dc9a98ce-5bb8-4cea-91aa-31432faf2668_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_7b208721-01b3-4296-9c5a-e8980ade287e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_dc9a98ce-5bb8-4cea-91aa-31432faf2668" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_7b208721-01b3-4296-9c5a-e8980ade287e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_e48cfed5-74ac-4bf2-8426-95c133ad56c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_7b208721-01b3-4296-9c5a-e8980ade287e" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_e48cfed5-74ac-4bf2-8426-95c133ad56c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_LoansReceivableFairValueDisclosureIndividuallyEvaluated_06ec4a6d-b26f-4ec2-ba30-49400ba8474a" xlink:href="bafn-20251231.xsd#bafn_LoansReceivableFairValueDisclosureIndividuallyEvaluated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_6b3c04f2-3caf-4d4b-a447-343967785158" xlink:to="loc_bafn_LoansReceivableFairValueDisclosureIndividuallyEvaluated_06ec4a6d-b26f-4ec2-ba30-49400ba8474a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_LoansReceivableFairValueDisclosureIndividuallyEvaluatedMeasurementInput_c45ffbe9-2fe6-4f65-bfee-daae1b7ee3b5" xlink:href="bafn-20251231.xsd#bafn_LoansReceivableFairValueDisclosureIndividuallyEvaluatedMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_6b3c04f2-3caf-4d4b-a447-343967785158" xlink:to="loc_bafn_LoansReceivableFairValueDisclosureIndividuallyEvaluatedMeasurementInput_c45ffbe9-2fe6-4f65-bfee-daae1b7ee3b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_OtherRealEstateOwnedFairValueDisclosure_7419f74f-1a93-403b-ad8b-ead5afd9b29b" xlink:href="bafn-20251231.xsd#bafn_OtherRealEstateOwnedFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_6b3c04f2-3caf-4d4b-a447-343967785158" xlink:to="loc_bafn_OtherRealEstateOwnedFairValueDisclosure_7419f74f-1a93-403b-ad8b-ead5afd9b29b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRealEstateOwnedMeasurementInput_6eb719c4-bb24-417b-b04f-5d9361549900" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherRealEstateOwnedMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_6b3c04f2-3caf-4d4b-a447-343967785158" xlink:to="loc_us-gaap_OtherRealEstateOwnedMeasurementInput_6eb719c4-bb24-417b-b04f-5d9361549900" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_RepossessedAssetsFairValueDisclosure_b1b9b977-15d2-404b-ab50-1dd882b2cd14" xlink:href="bafn-20251231.xsd#bafn_RepossessedAssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_6b3c04f2-3caf-4d4b-a447-343967785158" xlink:to="loc_bafn_RepossessedAssetsFairValueDisclosure_b1b9b977-15d2-404b-ab50-1dd882b2cd14" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_RepossessedAssetsFairValueDisclosureMeasurementInput_f06eecb3-adf5-46ca-beea-67bb4b973a88" xlink:href="bafn-20251231.xsd#bafn_RepossessedAssetsFairValueDisclosureMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_6b3c04f2-3caf-4d4b-a447-343967785158" xlink:to="loc_bafn_RepossessedAssetsFairValueDisclosureMeasurementInput_f06eecb3-adf5-46ca-beea-67bb4b973a88" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofAssetsandLiabilitiesNotCarriedatFairValueDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#FAIRVALUEScheduleofAssetsandLiabilitiesNotCarriedatFairValueDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/FAIRVALUEScheduleofAssetsandLiabilitiesNotCarriedatFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_5e19dfd1-8831-4999-8a41-436caacd4048" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_008de183-edd5-4379-9190-3faa1ac792fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_5e19dfd1-8831-4999-8a41-436caacd4048" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_008de183-edd5-4379-9190-3faa1ac792fc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a528e1d7-a0d1-47bc-b0b4-640606438375" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_008de183-edd5-4379-9190-3faa1ac792fc" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a528e1d7-a0d1-47bc-b0b4-640606438375" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_a528e1d7-a0d1-47bc-b0b4-640606438375_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a528e1d7-a0d1-47bc-b0b4-640606438375" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_a528e1d7-a0d1-47bc-b0b4-640606438375_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_c645b847-34d1-43d3-8759-4ec1940de6c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a528e1d7-a0d1-47bc-b0b4-640606438375" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_c645b847-34d1-43d3-8759-4ec1940de6c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_ee2ff965-bc74-40fa-978f-41132695b768" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_c645b847-34d1-43d3-8759-4ec1940de6c4" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_ee2ff965-bc74-40fa-978f-41132695b768" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_227940e8-88c2-4024-9744-85b08e33d977" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_c645b847-34d1-43d3-8759-4ec1940de6c4" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_227940e8-88c2-4024-9744-85b08e33d977" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_12ad94ac-b99e-4ad1-bc43-dac17c4e6405" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_c645b847-34d1-43d3-8759-4ec1940de6c4" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_12ad94ac-b99e-4ad1-bc43-dac17c4e6405" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_bdd3aba8-089a-44b4-9421-a165dfaad87c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_008de183-edd5-4379-9190-3faa1ac792fc" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_bdd3aba8-089a-44b4-9421-a165dfaad87c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_bdd3aba8-089a-44b4-9421-a165dfaad87c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_bdd3aba8-089a-44b4-9421-a165dfaad87c" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_bdd3aba8-089a-44b4-9421-a165dfaad87c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_69381638-44ac-4479-a194-29e920849909" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_bdd3aba8-089a-44b4-9421-a165dfaad87c" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_69381638-44ac-4479-a194-29e920849909" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_4ea0ce19-0ec5-48c6-b0e2-d7ed3759a1fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_69381638-44ac-4479-a194-29e920849909" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_4ea0ce19-0ec5-48c6-b0e2-d7ed3759a1fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_db82d80e-b925-40f3-ad0c-e8f71b1eab37" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_4ea0ce19-0ec5-48c6-b0e2-d7ed3759a1fa" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_db82d80e-b925-40f3-ad0c-e8f71b1eab37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_2ffcc658-106f-40a6-8dee-8208e7c184f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_4ea0ce19-0ec5-48c6-b0e2-d7ed3759a1fa" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_2ffcc658-106f-40a6-8dee-8208e7c184f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_a8be9ea7-0e62-4210-80f6-09eb769c36a1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_008de183-edd5-4379-9190-3faa1ac792fc" xlink:to="loc_us-gaap_FinancialInstrumentAxis_a8be9ea7-0e62-4210-80f6-09eb769c36a1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a8be9ea7-0e62-4210-80f6-09eb769c36a1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_a8be9ea7-0e62-4210-80f6-09eb769c36a1" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a8be9ea7-0e62-4210-80f6-09eb769c36a1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3c67cb14-a8bf-41f5-a5d8-98eeb3d3b3a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_a8be9ea7-0e62-4210-80f6-09eb769c36a1" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3c67cb14-a8bf-41f5-a5d8-98eeb3d3b3a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsMember_57dbd0e5-3763-4ee6-9d27-cff282f419b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3c67cb14-a8bf-41f5-a5d8-98eeb3d3b3a0" xlink:to="loc_us-gaap_CashAndCashEquivalentsMember_57dbd0e5-3763-4ee6-9d27-cff282f419b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BankTimeDepositsMember_c63ba254-dc19-4307-a40c-38681f3996d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BankTimeDepositsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3c67cb14-a8bf-41f5-a5d8-98eeb3d3b3a0" xlink:to="loc_us-gaap_BankTimeDepositsMember_c63ba254-dc19-4307-a40c-38681f3996d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_SBALoanMember_f0102e9c-3ed7-441e-bee4-4968d455b978" xlink:href="bafn-20251231.xsd#bafn_SBALoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3c67cb14-a8bf-41f5-a5d8-98eeb3d3b3a0" xlink:to="loc_bafn_SBALoanMember_f0102e9c-3ed7-441e-bee4-4968d455b978" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_NoninterestBearingDepositsMember_dcf222cf-f746-470d-ab5f-2a799e687786" xlink:href="bafn-20251231.xsd#bafn_NoninterestBearingDepositsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3c67cb14-a8bf-41f5-a5d8-98eeb3d3b3a0" xlink:to="loc_bafn_NoninterestBearingDepositsMember_dcf222cf-f746-470d-ab5f-2a799e687786" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestBearingDepositsMember_d246d7b2-dc6c-442e-acab-c1f7b8df9744" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestBearingDepositsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3c67cb14-a8bf-41f5-a5d8-98eeb3d3b3a0" xlink:to="loc_us-gaap_InterestBearingDepositsMember_d246d7b2-dc6c-442e-acab-c1f7b8df9744" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_BankSavingsAndMoneyMarketDepositsMember_d8874c36-9e52-4bcf-842e-9b2d49f434fa" xlink:href="bafn-20251231.xsd#bafn_BankSavingsAndMoneyMarketDepositsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3c67cb14-a8bf-41f5-a5d8-98eeb3d3b3a0" xlink:to="loc_bafn_BankSavingsAndMoneyMarketDepositsMember_d8874c36-9e52-4bcf-842e-9b2d49f434fa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_2c227447-4d88-4546-b399-7ffa2980b26d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_5e19dfd1-8831-4999-8a41-436caacd4048" xlink:to="loc_us-gaap_AssetsAbstract_2c227447-4d88-4546-b399-7ffa2980b26d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_9706ec5e-b115-4f92-b9e2-8e21a70e7515" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c227447-4d88-4546-b399-7ffa2980b26d" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_9706ec5e-b115-4f92-b9e2-8e21a70e7515" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_b506f30f-cfb6-43c8-acbc-ee3204579f49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c227447-4d88-4546-b399-7ffa2980b26d" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_b506f30f-cfb6-43c8-acbc-ee3204579f49" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiRestricted_eddee27f-73ba-4f00-8032-e77a0d71d5a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesFvNiRestricted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c227447-4d88-4546-b399-7ffa2980b26d" xlink:to="loc_us-gaap_EquitySecuritiesFvNiRestricted_eddee27f-73ba-4f00-8032-e77a0d71d5a0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableFairValueDisclosure_b7d2a360-2fd5-4a91-a5a9-b20123244288" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LoansReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c227447-4d88-4546-b399-7ffa2980b26d" xlink:to="loc_us-gaap_LoansReceivableFairValueDisclosure_b7d2a360-2fd5-4a91-a5a9-b20123244288" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestReceivable_394b0c7e-8e95-48e3-a876-2c3b6df02774" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c227447-4d88-4546-b399-7ffa2980b26d" xlink:to="loc_us-gaap_InterestReceivable_394b0c7e-8e95-48e3-a876-2c3b6df02774" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtFairValueAmount_9d87e59e-6a58-4dfd-89c1-74de85f9265b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetAtFairValueAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_2c227447-4d88-4546-b399-7ffa2980b26d" xlink:to="loc_us-gaap_ServicingAssetAtFairValueAmount_9d87e59e-6a58-4dfd-89c1-74de85f9265b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract_8618564a-c0c9-42bd-86c0-8c2b9d257de6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_5e19dfd1-8831-4999-8a41-436caacd4048" xlink:to="loc_us-gaap_LiabilitiesAbstract_8618564a-c0c9-42bd-86c0-8c2b9d257de6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsFairValueDisclosure_867284b5-5100-4a53-919f-38f341207986" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepositsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_8618564a-c0c9-42bd-86c0-8c2b9d257de6" xlink:to="loc_us-gaap_DepositsFairValueDisclosure_867284b5-5100-4a53-919f-38f341207986" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations_abf42148-070d-46ad-aa36-debdbc365eb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_8618564a-c0c9-42bd-86c0-8c2b9d257de6" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations_abf42148-070d-46ad-aa36-debdbc365eb5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableFairValueDisclosure_36f1d8cd-cce6-48c7-a54d-e2d67c1a0c51" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NotesPayableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_8618564a-c0c9-42bd-86c0-8c2b9d257de6" xlink:to="loc_us-gaap_NotesPayableFairValueDisclosure_36f1d8cd-cce6-48c7-a54d-e2d67c1a0c51" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesFairValueDisclosure_40b17b58-c368-431b-ac39-786cb29b55ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedLiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_8618564a-c0c9-42bd-86c0-8c2b9d257de6" xlink:to="loc_us-gaap_AccruedLiabilitiesFairValueDisclosure_40b17b58-c368-431b-ac39-786cb29b55ff" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/GOVERNMENTGUARANTEEDLOANSERVICINGACTIVITIESNarrativeDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#GOVERNMENTGUARANTEEDLOANSERVICINGACTIVITIESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/GOVERNMENTGUARANTEEDLOANSERVICINGACTIVITIESNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_b0ff9a9a-f92d-4e87-a2bb-68ee9b2f20a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetsAtAmortizedValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetsAtAmortizedValueTable_dc717f50-7c9e-442e-aafc-7ed4f86c3711" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetsAtAmortizedValueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_b0ff9a9a-f92d-4e87-a2bb-68ee9b2f20a8" xlink:to="loc_us-gaap_ServicingAssetsAtAmortizedValueTable_dc717f50-7c9e-442e-aafc-7ed4f86c3711" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_5501ab5c-4b46-4e3b-8b73-f6b929d5bfae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueTable_dc717f50-7c9e-442e-aafc-7ed4f86c3711" xlink:to="loc_us-gaap_FinancialInstrumentAxis_5501ab5c-4b46-4e3b-8b73-f6b929d5bfae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5501ab5c-4b46-4e3b-8b73-f6b929d5bfae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_5501ab5c-4b46-4e3b-8b73-f6b929d5bfae" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5501ab5c-4b46-4e3b-8b73-f6b929d5bfae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_90b2eadc-15f7-47e6-83d5-bec67c2df97d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_5501ab5c-4b46-4e3b-8b73-f6b929d5bfae" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_90b2eadc-15f7-47e6-83d5-bec67c2df97d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_SBALoanMember_9439f107-1de9-48e2-893d-98ac77b26312" xlink:href="bafn-20251231.xsd#bafn_SBALoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_90b2eadc-15f7-47e6-83d5-bec67c2df97d" xlink:to="loc_bafn_SBALoanMember_9439f107-1de9-48e2-893d-98ac77b26312" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_SBA7aLoansMember_019bcc15-c6fe-7f14-a6ee-6119aca3b626" xlink:href="bafn-20251231.xsd#bafn_SBA7aLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_90b2eadc-15f7-47e6-83d5-bec67c2df97d" xlink:to="loc_bafn_SBA7aLoansMember_019bcc15-c6fe-7f14-a6ee-6119aca3b626" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ebfba43e-081a-4de7-a992-11892d6fa1ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueTable_dc717f50-7c9e-442e-aafc-7ed4f86c3711" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ebfba43e-081a-4de7-a992-11892d6fa1ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ebfba43e-081a-4de7-a992-11892d6fa1ef_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ebfba43e-081a-4de7-a992-11892d6fa1ef" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ebfba43e-081a-4de7-a992-11892d6fa1ef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7729f1a3-6910-499d-bd93-328524394592" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ebfba43e-081a-4de7-a992-11892d6fa1ef" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7729f1a3-6910-499d-bd93-328524394592" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_80c21f5a-5acf-451d-af46-6ded3ba64483" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7729f1a3-6910-499d-bd93-328524394592" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_80c21f5a-5acf-451d-af46-6ded3ba64483" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_c1e335a9-28f7-4838-8ae4-8bdcd97acbb0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueTable_dc717f50-7c9e-442e-aafc-7ed4f86c3711" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_c1e335a9-28f7-4838-8ae4-8bdcd97acbb0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_c1e335a9-28f7-4838-8ae4-8bdcd97acbb0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_c1e335a9-28f7-4838-8ae4-8bdcd97acbb0" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_c1e335a9-28f7-4838-8ae4-8bdcd97acbb0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_d697c5bf-c09f-459b-8baf-796f2f839ef3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_c1e335a9-28f7-4838-8ae4-8bdcd97acbb0" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_d697c5bf-c09f-459b-8baf-796f2f839ef3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_07f41519-a556-4660-9184-2a30fab3f058" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_d697c5bf-c09f-459b-8baf-796f2f839ef3" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_07f41519-a556-4660-9184-2a30fab3f058" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_e8e5d3ea-59dd-43fe-b4bd-68bdd9c908e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_07f41519-a556-4660-9184-2a30fab3f058" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_e8e5d3ea-59dd-43fe-b4bd-68bdd9c908e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_LoansAndLeasesReceivableServicedForOtherParty_2b22266b-4bc2-4b56-8bb3-56e076cd2dee" xlink:href="bafn-20251231.xsd#bafn_LoansAndLeasesReceivableServicedForOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_b0ff9a9a-f92d-4e87-a2bb-68ee9b2f20a8" xlink:to="loc_bafn_LoansAndLeasesReceivableServicedForOtherParty_2b22266b-4bc2-4b56-8bb3-56e076cd2dee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_LoansAndLeasesReceivableServicedForOtherPartyGuaranteedBalance_09b16517-a1c4-4bad-b4df-da7c81ffa117" xlink:href="bafn-20251231.xsd#bafn_LoansAndLeasesReceivableServicedForOtherPartyGuaranteedBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_b0ff9a9a-f92d-4e87-a2bb-68ee9b2f20a8" xlink:to="loc_bafn_LoansAndLeasesReceivableServicedForOtherPartyGuaranteedBalance_09b16517-a1c4-4bad-b4df-da7c81ffa117" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ServicingAssetsUnpaidPrincipalLoanBalance_12a9c90d-9483-44a6-97c3-961f0c17ec47" xlink:href="bafn-20251231.xsd#bafn_ServicingAssetsUnpaidPrincipalLoanBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_b0ff9a9a-f92d-4e87-a2bb-68ee9b2f20a8" xlink:to="loc_bafn_ServicingAssetsUnpaidPrincipalLoanBalance_12a9c90d-9483-44a6-97c3-961f0c17ec47" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtFairValueAmount_229efea4-f900-41cd-bc80-a75bedd419fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetAtFairValueAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_b0ff9a9a-f92d-4e87-a2bb-68ee9b2f20a8" xlink:to="loc_us-gaap_ServicingAssetAtFairValueAmount_229efea4-f900-41cd-bc80-a75bedd419fe" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueDiscountRate_c8e2539f-5123-4793-b9b8-cd9b5a54e971" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_b0ff9a9a-f92d-4e87-a2bb-68ee9b2f20a8" xlink:to="loc_us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueDiscountRate_c8e2539f-5123-4793-b9b8-cd9b5a54e971" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValuePrepaymentSpeed_3943e783-4a91-441f-9b44-5e1662b12b80" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValuePrepaymentSpeed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_b0ff9a9a-f92d-4e87-a2bb-68ee9b2f20a8" xlink:to="loc_us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValuePrepaymentSpeed_3943e783-4a91-441f-9b44-5e1662b12b80" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/GOVERNMENTGUARANTEEDLOANSERVICINGACTIVITIESScheduleofActivityforGovernmentGuaranteedLoanServicingRightsDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#GOVERNMENTGUARANTEEDLOANSERVICINGACTIVITIESScheduleofActivityforGovernmentGuaranteedLoanServicingRightsDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/GOVERNMENTGUARANTEEDLOANSERVICINGACTIVITIESScheduleofActivityforGovernmentGuaranteedLoanServicingRightsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_70f31077-a975-4f13-a07b-1abe7c7c69e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetsAtAmortizedValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetsAtAmortizedValueTable_437bbe06-e7f2-4643-8cc8-99018bc1ccbb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetsAtAmortizedValueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_70f31077-a975-4f13-a07b-1abe7c7c69e9" xlink:to="loc_us-gaap_ServicingAssetsAtAmortizedValueTable_437bbe06-e7f2-4643-8cc8-99018bc1ccbb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_6ad2f4b7-2cd9-4b32-8a04-7eecf3e73b53" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueTable_437bbe06-e7f2-4643-8cc8-99018bc1ccbb" xlink:to="loc_us-gaap_FinancialInstrumentAxis_6ad2f4b7-2cd9-4b32-8a04-7eecf3e73b53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6ad2f4b7-2cd9-4b32-8a04-7eecf3e73b53_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_6ad2f4b7-2cd9-4b32-8a04-7eecf3e73b53" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6ad2f4b7-2cd9-4b32-8a04-7eecf3e73b53_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_efb20c84-ceba-4a76-84d5-bc3f3fd35de7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_6ad2f4b7-2cd9-4b32-8a04-7eecf3e73b53" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_efb20c84-ceba-4a76-84d5-bc3f3fd35de7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_SBALoanMember_ec30af26-40b6-4a63-bc42-53541380d21f" xlink:href="bafn-20251231.xsd#bafn_SBALoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_efb20c84-ceba-4a76-84d5-bc3f3fd35de7" xlink:to="loc_bafn_SBALoanMember_ec30af26-40b6-4a63-bc42-53541380d21f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtAmortizedValueBalanceRollForward_f71977cd-3149-4439-a90a-8dc7132973ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetAtAmortizedValueBalanceRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_70f31077-a975-4f13-a07b-1abe7c7c69e9" xlink:to="loc_us-gaap_ServicingAssetAtAmortizedValueBalanceRollForward_f71977cd-3149-4439-a90a-8dc7132973ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtAmortizedValue_47e84e69-956f-4b13-9ead-c74fe09b86df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetAtAmortizedValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetAtAmortizedValueBalanceRollForward_f71977cd-3149-4439-a90a-8dc7132973ed" xlink:to="loc_us-gaap_ServicingAssetAtAmortizedValue_47e84e69-956f-4b13-9ead-c74fe09b86df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtAmortizedValueAdditions_42eeb7c0-e5c6-4c83-a9c2-0c818e09cef3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetAtAmortizedValueAdditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetAtAmortizedValueBalanceRollForward_f71977cd-3149-4439-a90a-8dc7132973ed" xlink:to="loc_us-gaap_ServicingAssetAtAmortizedValueAdditions_42eeb7c0-e5c6-4c83-a9c2-0c818e09cef3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtAmortizedValueDisposals_019bcc17-b2a0-7f8a-937f-63aee23316cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetAtAmortizedValueDisposals"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetAtAmortizedValueBalanceRollForward_f71977cd-3149-4439-a90a-8dc7132973ed" xlink:to="loc_us-gaap_ServicingAssetAtAmortizedValueDisposals_019bcc17-b2a0-7f8a-937f-63aee23316cd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtAmortizedValueAmortization1_39bf719e-20e8-436f-ab3d-5717dd329ff3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetAtAmortizedValueAmortization1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetAtAmortizedValueBalanceRollForward_f71977cd-3149-4439-a90a-8dc7132973ed" xlink:to="loc_us-gaap_ServicingAssetAtAmortizedValueAmortization1_39bf719e-20e8-436f-ab3d-5717dd329ff3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtAmortizedValue_5d3b31a8-5c65-4a02-9c85-47466e150e23" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetAtAmortizedValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/GOVERNMENTGUARANTEEDLOANSERVICINGACTIVITIESScheduleofNetGainonSaleofGovernmentGuaranteedLoansDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#GOVERNMENTGUARANTEEDLOANSERVICINGACTIVITIESScheduleofNetGainonSaleofGovernmentGuaranteedLoansDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/GOVERNMENTGUARANTEEDLOANSERVICINGACTIVITIESScheduleofNetGainonSaleofGovernmentGuaranteedLoansDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_8465c2d6-53d0-45ab-b17e-57945d0e751c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetsAtAmortizedValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetsAtAmortizedValueTable_f1e00614-b7dd-4ed5-b1c2-a99cf89c0b11" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServicingAssetsAtAmortizedValueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_8465c2d6-53d0-45ab-b17e-57945d0e751c" xlink:to="loc_us-gaap_ServicingAssetsAtAmortizedValueTable_f1e00614-b7dd-4ed5-b1c2-a99cf89c0b11" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_08eb87c5-a9f9-459e-a4cd-6eb2092a8db7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueTable_f1e00614-b7dd-4ed5-b1c2-a99cf89c0b11" xlink:to="loc_us-gaap_FinancialInstrumentAxis_08eb87c5-a9f9-459e-a4cd-6eb2092a8db7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_08eb87c5-a9f9-459e-a4cd-6eb2092a8db7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_08eb87c5-a9f9-459e-a4cd-6eb2092a8db7" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_08eb87c5-a9f9-459e-a4cd-6eb2092a8db7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_c5c4de73-c81a-4641-bb73-3761e001c2fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_08eb87c5-a9f9-459e-a4cd-6eb2092a8db7" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_c5c4de73-c81a-4641-bb73-3761e001c2fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_SBALoanMember_d873eff9-f011-44de-9db8-5f03f02c5248" xlink:href="bafn-20251231.xsd#bafn_SBALoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_c5c4de73-c81a-4641-bb73-3761e001c2fd" xlink:to="loc_bafn_SBALoanMember_d873eff9-f011-44de-9db8-5f03f02c5248" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_GainLossOnSalesOfGuaranteedLoansNet_19857db4-d77b-4a29-81a5-caa0a90a7cc2" xlink:href="bafn-20251231.xsd#bafn_GainLossOnSalesOfGuaranteedLoansNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_8465c2d6-53d0-45ab-b17e-57945d0e751c" xlink:to="loc_bafn_GainLossOnSalesOfGuaranteedLoansNet_19857db4-d77b-4a29-81a5-caa0a90a7cc2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ServicingAssetFairValueOfServicingRightsCreated_e2a216ba-f693-4ef1-98d3-7e89b647fe33" xlink:href="bafn-20251231.xsd#bafn_ServicingAssetFairValueOfServicingRightsCreated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_8465c2d6-53d0-45ab-b17e-57945d0e751c" xlink:to="loc_bafn_ServicingAssetFairValueOfServicingRightsCreated_e2a216ba-f693-4ef1-98d3-7e89b647fe33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSalesOfLoansNet_1fb9ec5b-4bda-4b9f-961e-3f36a8f53a38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSalesOfLoansNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ServicingAssetsAtAmortizedValueLineItems_8465c2d6-53d0-45ab-b17e-57945d0e751c" xlink:to="loc_us-gaap_GainLossOnSalesOfLoansNet_1fb9ec5b-4bda-4b9f-961e-3f36a8f53a38" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/PREMISESANDEQUIPMENTScheduleofPremisesandEquipmentDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#PREMISESANDEQUIPMENTScheduleofPremisesandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/PREMISESANDEQUIPMENTScheduleofPremisesandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_ac50f4ef-b885-44e6-9511-8047ca67962a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_301bcedf-c484-4ebe-96ce-3735b0be67b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_ac50f4ef-b885-44e6-9511-8047ca67962a" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_301bcedf-c484-4ebe-96ce-3735b0be67b3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_fbd21130-0549-4add-9564-602ad4613e1f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_301bcedf-c484-4ebe-96ce-3735b0be67b3" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_fbd21130-0549-4add-9564-602ad4613e1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_fbd21130-0549-4add-9564-602ad4613e1f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_fbd21130-0549-4add-9564-602ad4613e1f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_fbd21130-0549-4add-9564-602ad4613e1f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a2e5e15a-bf52-4db1-9dbc-7ed809bc6562" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_fbd21130-0549-4add-9564-602ad4613e1f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a2e5e15a-bf52-4db1-9dbc-7ed809bc6562" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandAndLandImprovementsMember_20226d13-b8ec-44f9-a796-184153cc11c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LandAndLandImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a2e5e15a-bf52-4db1-9dbc-7ed809bc6562" xlink:to="loc_us-gaap_LandAndLandImprovementsMember_20226d13-b8ec-44f9-a796-184153cc11c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_763190f3-ebec-4f15-be1e-1b526834fd41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingAndBuildingImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a2e5e15a-bf52-4db1-9dbc-7ed809bc6562" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_763190f3-ebec-4f15-be1e-1b526834fd41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_d64bec32-4dc2-4d79-91a5-00f0d8bf336e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a2e5e15a-bf52-4db1-9dbc-7ed809bc6562" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_d64bec32-4dc2-4d79-91a5-00f0d8bf336e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_FurnitureFixturesAndEquipmentMember_313b5f58-b3b0-4411-a2f0-882725b06320" xlink:href="bafn-20251231.xsd#bafn_FurnitureFixturesAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a2e5e15a-bf52-4db1-9dbc-7ed809bc6562" xlink:to="loc_bafn_FurnitureFixturesAndEquipmentMember_313b5f58-b3b0-4411-a2f0-882725b06320" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_7d9c5eb8-427d-4240-af28-fb45d8357f84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a2e5e15a-bf52-4db1-9dbc-7ed809bc6562" xlink:to="loc_us-gaap_ConstructionInProgressMember_7d9c5eb8-427d-4240-af28-fb45d8357f84" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_25abde81-46be-42fa-833d-524c00d49f7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_301bcedf-c484-4ebe-96ce-3735b0be67b3" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_25abde81-46be-42fa-833d-524c00d49f7f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_25abde81-46be-42fa-833d-524c00d49f7f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_25abde81-46be-42fa-833d-524c00d49f7f" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_25abde81-46be-42fa-833d-524c00d49f7f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_b386b643-28f9-457c-85af-bda1dcd92540" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_25abde81-46be-42fa-833d-524c00d49f7f" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_b386b643-28f9-457c-85af-bda1dcd92540" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_a8d9983b-d3ee-45ea-a46b-418d84c67882" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_b386b643-28f9-457c-85af-bda1dcd92540" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_a8d9983b-d3ee-45ea-a46b-418d84c67882" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_451f4f3c-99e9-4be8-8621-3a16c2a971d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_301bcedf-c484-4ebe-96ce-3735b0be67b3" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_451f4f3c-99e9-4be8-8621-3a16c2a971d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_451f4f3c-99e9-4be8-8621-3a16c2a971d4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_451f4f3c-99e9-4be8-8621-3a16c2a971d4" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_451f4f3c-99e9-4be8-8621-3a16c2a971d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_2c5de4c7-bed5-42ab-ad23-a6f51d9e377c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_451f4f3c-99e9-4be8-8621-3a16c2a971d4" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_2c5de4c7-bed5-42ab-ad23-a6f51d9e377c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_NationwideResidentialMortgageLoanProductionOperationsMember_1b4e0f7d-62be-451c-9df4-0ef05afea104" xlink:href="bafn-20251231.xsd#bafn_NationwideResidentialMortgageLoanProductionOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_2c5de4c7-bed5-42ab-ad23-a6f51d9e377c" xlink:to="loc_bafn_NationwideResidentialMortgageLoanProductionOperationsMember_1b4e0f7d-62be-451c-9df4-0ef05afea104" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_f2daa435-b25c-46df-bdb6-bec87a8b27c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_ac50f4ef-b885-44e6-9511-8047ca67962a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_f2daa435-b25c-46df-bdb6-bec87a8b27c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_778ce66c-e78e-4dc3-aad0-d4e356a8c37d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_ac50f4ef-b885-44e6-9511-8047ca67962a" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_778ce66c-e78e-4dc3-aad0-d4e356a8c37d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_6036e7cf-55a6-4e85-9d27-df264b5bb3ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_ac50f4ef-b885-44e6-9511-8047ca67962a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_6036e7cf-55a6-4e85-9d27-df264b5bb3ac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipment_eb33cece-6dfd-4210-86f1-a33503f38411" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_ac50f4ef-b885-44e6-9511-8047ca67962a" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipment_eb33cece-6dfd-4210-86f1-a33503f38411" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/LEASESScheduleofTotalLeaseCostandSupplementalInformationDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#LEASESScheduleofTotalLeaseCostandSupplementalInformationDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/LEASESScheduleofTotalLeaseCostandSupplementalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e00f7c81-4efa-431d-b8bb-fbfec7a24d7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_d69a1ae6-987d-40b7-a7f9-c137350b7bd5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e00f7c81-4efa-431d-b8bb-fbfec7a24d7f" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_d69a1ae6-987d-40b7-a7f9-c137350b7bd5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_0b009b44-9260-4543-bd94-f99456e8de37" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_d69a1ae6-987d-40b7-a7f9-c137350b7bd5" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_0b009b44-9260-4543-bd94-f99456e8de37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_0b009b44-9260-4543-bd94-f99456e8de37_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_0b009b44-9260-4543-bd94-f99456e8de37" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_0b009b44-9260-4543-bd94-f99456e8de37_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_0ec8568c-8f2b-4568-9554-116787435f94" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_0b009b44-9260-4543-bd94-f99456e8de37" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_0ec8568c-8f2b-4568-9554-116787435f94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_32ffbaf2-f65a-4c0b-8474-6bc116116ba1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_0ec8568c-8f2b-4568-9554-116787435f94" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_32ffbaf2-f65a-4c0b-8474-6bc116116ba1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b6d9dc45-10ab-4eba-bbb0-960440f426cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_d69a1ae6-987d-40b7-a7f9-c137350b7bd5" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b6d9dc45-10ab-4eba-bbb0-960440f426cd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b6d9dc45-10ab-4eba-bbb0-960440f426cd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b6d9dc45-10ab-4eba-bbb0-960440f426cd" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b6d9dc45-10ab-4eba-bbb0-960440f426cd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_980be791-3e7d-4ff0-8392-ff3f742ccf80" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b6d9dc45-10ab-4eba-bbb0-960440f426cd" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_980be791-3e7d-4ff0-8392-ff3f742ccf80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_NationwideResidentialMortgageLoanProductionOperationsMember_ab20b988-ad44-4f95-a66f-2f5b498d135e" xlink:href="bafn-20251231.xsd#bafn_NationwideResidentialMortgageLoanProductionOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_980be791-3e7d-4ff0-8392-ff3f742ccf80" xlink:to="loc_bafn_NationwideResidentialMortgageLoanProductionOperationsMember_ab20b988-ad44-4f95-a66f-2f5b498d135e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost_1b804e24-a7f3-45b2-aee0-a80ab516c35f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e00f7c81-4efa-431d-b8bb-fbfec7a24d7f" xlink:to="loc_us-gaap_OperatingLeaseCost_1b804e24-a7f3-45b2-aee0-a80ab516c35f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ShortTermLeaseCostIncome_59919eea-5964-4cbe-83f1-63dba85db5d0" xlink:href="bafn-20251231.xsd#bafn_ShortTermLeaseCostIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e00f7c81-4efa-431d-b8bb-fbfec7a24d7f" xlink:to="loc_bafn_ShortTermLeaseCostIncome_59919eea-5964-4cbe-83f1-63dba85db5d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCost_e3d32a24-c873-4b8c-8374-57bbb06c46c1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e00f7c81-4efa-431d-b8bb-fbfec7a24d7f" xlink:to="loc_us-gaap_LeaseCost_e3d32a24-c873-4b8c-8374-57bbb06c46c1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_a5495795-a567-4e86-841e-01a14be04181" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e00f7c81-4efa-431d-b8bb-fbfec7a24d7f" xlink:to="loc_us-gaap_OperatingLeasePayments_a5495795-a567-4e86-841e-01a14be04181" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_e31eb5fe-c9ee-41f2-9c99-b15b38222e18" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_e00f7c81-4efa-431d-b8bb-fbfec7a24d7f" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_e31eb5fe-c9ee-41f2-9c99-b15b38222e18" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/OTHERBORROWINGSDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#OTHERBORROWINGSDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/OTHERBORROWINGSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_7143dc2a-3bbb-43b5-9758-2377a2831426" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_us-gaap_DebtInstrumentTable_7143dc2a-3bbb-43b5-9758-2377a2831426" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_0c794d8b-2788-4708-acc3-9ca84fa8545b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7143dc2a-3bbb-43b5-9758-2377a2831426" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_0c794d8b-2788-4708-acc3-9ca84fa8545b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_0c794d8b-2788-4708-acc3-9ca84fa8545b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_0c794d8b-2788-4708-acc3-9ca84fa8545b" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_0c794d8b-2788-4708-acc3-9ca84fa8545b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_4269d11a-a612-4885-a462-6b08b9e86a53" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_0c794d8b-2788-4708-acc3-9ca84fa8545b" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_4269d11a-a612-4885-a462-6b08b9e86a53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalReserveBankAdvancesMember_ca288d4b-a8ed-4365-b9ec-7c75508f92a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FederalReserveBankAdvancesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_4269d11a-a612-4885-a462-6b08b9e86a53" xlink:to="loc_us-gaap_FederalReserveBankAdvancesMember_ca288d4b-a8ed-4365-b9ec-7c75508f92a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesMember_7465bfb0-1998-4dc2-a0fe-bc10759b981e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FederalHomeLoanBankAdvancesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_4269d11a-a612-4885-a462-6b08b9e86a53" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesMember_7465bfb0-1998-4dc2-a0fe-bc10759b981e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_bc205de4-187e-42c0-a8eb-0493238c91c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7143dc2a-3bbb-43b5-9758-2377a2831426" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_bc205de4-187e-42c0-a8eb-0493238c91c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_bc205de4-187e-42c0-a8eb-0493238c91c2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_bc205de4-187e-42c0-a8eb-0493238c91c2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_bc205de4-187e-42c0-a8eb-0493238c91c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_9c907a4f-c6a2-4656-9319-c5286e17bec2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_bc205de4-187e-42c0-a8eb-0493238c91c2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_9c907a4f-c6a2-4656-9319-c5286e17bec2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalReserveBankAdvancesMember_8f2958d9-0bcc-425b-b7de-2e0e7d802581" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FederalReserveBankAdvancesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_9c907a4f-c6a2-4656-9319-c5286e17bec2" xlink:to="loc_us-gaap_FederalReserveBankAdvancesMember_8f2958d9-0bcc-425b-b7de-2e0e7d802581" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedDebtMember_c647c5bc-7e9e-4f29-94a8-91676ec6473f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubordinatedDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_9c907a4f-c6a2-4656-9319-c5286e17bec2" xlink:to="loc_us-gaap_SubordinatedDebtMember_c647c5bc-7e9e-4f29-94a8-91676ec6473f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019bcc29-9abe-72b4-8611-d7dc906c8623" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_9c907a4f-c6a2-4656-9319-c5286e17bec2" xlink:to="loc_us-gaap_SeniorNotesMember_019bcc29-9abe-72b4-8611-d7dc906c8623" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_bc3512e7-e4a4-4efa-ab22-55f4992b6d38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NotesPayableOtherPayablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_9c907a4f-c6a2-4656-9319-c5286e17bec2" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_bc3512e7-e4a4-4efa-ab22-55f4992b6d38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_b7cc77a4-1558-42b1-b927-54c6fa036cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7143dc2a-3bbb-43b5-9758-2377a2831426" xlink:to="loc_us-gaap_CreditFacilityAxis_b7cc77a4-1558-42b1-b927-54c6fa036cb5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_b7cc77a4-1558-42b1-b927-54c6fa036cb5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_b7cc77a4-1558-42b1-b927-54c6fa036cb5" xlink:to="loc_us-gaap_CreditFacilityDomain_b7cc77a4-1558-42b1-b927-54c6fa036cb5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_410e6f84-e8d4-46a1-b30e-b14d5e157b0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_b7cc77a4-1558-42b1-b927-54c6fa036cb5" xlink:to="loc_us-gaap_CreditFacilityDomain_410e6f84-e8d4-46a1-b30e-b14d5e157b0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_33eee9ad-2ccc-4b7e-8f84-98fcd1170df7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_410e6f84-e8d4-46a1-b30e-b14d5e157b0d" xlink:to="loc_us-gaap_SecuredDebtMember_33eee9ad-2ccc-4b7e-8f84-98fcd1170df7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_785c2e50-1b4e-4e6c-8ab4-5219a0b50a13" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7143dc2a-3bbb-43b5-9758-2377a2831426" xlink:to="loc_us-gaap_FinancialInstrumentAxis_785c2e50-1b4e-4e6c-8ab4-5219a0b50a13" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_785c2e50-1b4e-4e6c-8ab4-5219a0b50a13_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_785c2e50-1b4e-4e6c-8ab4-5219a0b50a13" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_785c2e50-1b4e-4e6c-8ab4-5219a0b50a13_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b4a31375-4e07-4dca-9330-5485e0170737" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_785c2e50-1b4e-4e6c-8ab4-5219a0b50a13" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b4a31375-4e07-4dca-9330-5485e0170737" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialLoanMember_28287c9c-ff76-4024-9082-11e0d3ab9aa4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b4a31375-4e07-4dca-9330-5485e0170737" xlink:to="loc_us-gaap_CommercialLoanMember_28287c9c-ff76-4024-9082-11e0d3ab9aa4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_81dd8046-d917-4a72-b466-0e2a12e7ae6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7143dc2a-3bbb-43b5-9758-2377a2831426" xlink:to="loc_us-gaap_DebtInstrumentAxis_81dd8046-d917-4a72-b466-0e2a12e7ae6c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_81dd8046-d917-4a72-b466-0e2a12e7ae6c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_81dd8046-d917-4a72-b466-0e2a12e7ae6c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_81dd8046-d917-4a72-b466-0e2a12e7ae6c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_3f3b2ad3-e110-424c-85bf-061d9552c0d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_81dd8046-d917-4a72-b466-0e2a12e7ae6c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_3f3b2ad3-e110-424c-85bf-061d9552c0d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_June2031SubordinatedNotesMember_26499b6a-c45d-49ee-b8f0-e599dfbbe27a" xlink:href="bafn-20251231.xsd#bafn_June2031SubordinatedNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_3f3b2ad3-e110-424c-85bf-061d9552c0d0" xlink:to="loc_bafn_June2031SubordinatedNotesMember_26499b6a-c45d-49ee-b8f0-e599dfbbe27a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_June2026AmendmentNotesMember_019bcc2a-ed6f-725d-bfd0-f386ad280da2" xlink:href="bafn-20251231.xsd#bafn_June2026AmendmentNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_3f3b2ad3-e110-424c-85bf-061d9552c0d0" xlink:to="loc_bafn_June2026AmendmentNotesMember_019bcc2a-ed6f-725d-bfd0-f386ad280da2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_AmortizingNotePayableMember_5f3e2fcc-4000-4b95-988a-b685e28bf9ec" xlink:href="bafn-20251231.xsd#bafn_AmortizingNotePayableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_3f3b2ad3-e110-424c-85bf-061d9552c0d0" xlink:to="loc_bafn_AmortizingNotePayableMember_5f3e2fcc-4000-4b95-988a-b685e28bf9ec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_41f94821-d77f-4428-9fb5-8f5e7e5fc3fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7143dc2a-3bbb-43b5-9758-2377a2831426" xlink:to="loc_us-gaap_VariableRateAxis_41f94821-d77f-4428-9fb5-8f5e7e5fc3fa" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_41f94821-d77f-4428-9fb5-8f5e7e5fc3fa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_41f94821-d77f-4428-9fb5-8f5e7e5fc3fa" xlink:to="loc_us-gaap_VariableRateDomain_41f94821-d77f-4428-9fb5-8f5e7e5fc3fa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_315b0c5e-c383-4708-8334-af05527da7aa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_41f94821-d77f-4428-9fb5-8f5e7e5fc3fa" xlink:to="loc_us-gaap_VariableRateDomain_315b0c5e-c383-4708-8334-af05527da7aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_7044b2bf-533f-480f-8cdc-a6843a9dc43b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_315b0c5e-c383-4708-8334-af05527da7aa" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_7044b2bf-533f-480f-8cdc-a6843a9dc43b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrimeRateMember_c0ade643-14f7-447d-8564-971f415938e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PrimeRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_315b0c5e-c383-4708-8334-af05527da7aa" xlink:to="loc_us-gaap_PrimeRateMember_c0ade643-14f7-447d-8564-971f415938e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_473c60ab-ca43-46cb-ac08-2d692e2522e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_us-gaap_ShortTermBorrowings_473c60ab-ca43-46cb-ac08-2d692e2522e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1_6c72546c-9c65-44bd-9fa1-8f586adc2c31" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1_6c72546c-9c65-44bd-9fa1-8f586adc2c31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds_e4ba6f84-e845-4962-8f2a-e92b8c60ec7a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds_e4ba6f84-e845-4962-8f2a-e92b8c60ec7a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_0d7a7f0b-9794-49de-9b27-4995837df399" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_0d7a7f0b-9794-49de-9b27-4995837df399" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_5497f1e3-8000-4d7e-a2d4-cc8a4e6c5872" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_5497f1e3-8000-4d7e-a2d4-cc8a4e6c5872" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_DebtInstrumentRedemptionPeriod_5fc52fe9-96ef-43b7-a634-6b83c9ddc8b6" xlink:href="bafn-20251231.xsd#bafn_DebtInstrumentRedemptionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_bafn_DebtInstrumentRedemptionPeriod_5fc52fe9-96ef-43b7-a634-6b83c9ddc8b6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_10e97376-168e-4623-8c4d-3243cf45bbfe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_10e97376-168e-4623-8c4d-3243cf45bbfe" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_DebtInstrumentInterestRateInitialTerm_d8fd89c8-8a79-432e-8ce8-5593125b7a4d" xlink:href="bafn-20251231.xsd#bafn_DebtInstrumentInterestRateInitialTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_bafn_DebtInstrumentInterestRateInitialTerm_d8fd89c8-8a79-432e-8ce8-5593125b7a4d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_DebtInstrumentInterestRateFinalTerm_218d8363-0d09-46ec-a0fb-ddcfab124e05" xlink:href="bafn-20251231.xsd#bafn_DebtInstrumentInterestRateFinalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_bafn_DebtInstrumentInterestRateFinalTerm_218d8363-0d09-46ec-a0fb-ddcfab124e05" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_4a2ba62f-8fbd-48a4-9084-db968e317c04" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_4a2ba62f-8fbd-48a4-9084-db968e317c04" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateIncreaseDecrease_019bcc2b-d0bb-70e7-a940-ecc44a57436f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_us-gaap_DebtInstrumentInterestRateIncreaseDecrease_019bcc2b-d0bb-70e7-a940-ecc44a57436f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedDebt_ebf9f33a-4ea3-4c8a-9392-18a170611bea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubordinatedDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_us-gaap_SubordinatedDebt_ebf9f33a-4ea3-4c8a-9392-18a170611bea" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayable_3d25d52e-69ef-4a12-82d9-e7914731ad38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NotesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_us-gaap_NotesPayable_3d25d52e-69ef-4a12-82d9-e7914731ad38" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_DebtInstrumentCollateralPercent_4379684f-8b4d-44fa-8359-74f9d5e13b3c" xlink:href="bafn-20251231.xsd#bafn_DebtInstrumentCollateralPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4f2f6578-ca41-43d0-9b39-474c27956aa4" xlink:to="loc_bafn_DebtInstrumentCollateralPercent_4379684f-8b4d-44fa-8359-74f9d5e13b3c" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/STOCKBASEDCOMPENSATIONNarrativeDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#STOCKBASEDCOMPENSATIONNarrativeDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/STOCKBASEDCOMPENSATIONNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2bbff769-e703-4c69-ab04-e9549f97a123" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2bbff769-e703-4c69-ab04-e9549f97a123" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_b49a473a-f5b1-44bd-a2ee-c91efa4d4add" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2bbff769-e703-4c69-ab04-e9549f97a123" xlink:to="loc_us-gaap_PlanNameAxis_b49a473a-f5b1-44bd-a2ee-c91efa4d4add" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_b49a473a-f5b1-44bd-a2ee-c91efa4d4add_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_b49a473a-f5b1-44bd-a2ee-c91efa4d4add" xlink:to="loc_us-gaap_PlanNameDomain_b49a473a-f5b1-44bd-a2ee-c91efa4d4add_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_5c23bc08-69d3-4cdc-bcd5-bc82e67779e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_b49a473a-f5b1-44bd-a2ee-c91efa4d4add" xlink:to="loc_us-gaap_PlanNameDomain_5c23bc08-69d3-4cdc-bcd5-bc82e67779e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_EquityPlanMember_d750d6e8-0078-47d6-9cd5-82132fe25735" xlink:href="bafn-20251231.xsd#bafn_EquityPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_5c23bc08-69d3-4cdc-bcd5-bc82e67779e2" xlink:to="loc_bafn_EquityPlanMember_d750d6e8-0078-47d6-9cd5-82132fe25735" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_9bc10e4e-9b43-4dea-b6e9-ceac44c31dfe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2bbff769-e703-4c69-ab04-e9549f97a123" xlink:to="loc_us-gaap_AwardTypeAxis_9bc10e4e-9b43-4dea-b6e9-ceac44c31dfe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9bc10e4e-9b43-4dea-b6e9-ceac44c31dfe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_9bc10e4e-9b43-4dea-b6e9-ceac44c31dfe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9bc10e4e-9b43-4dea-b6e9-ceac44c31dfe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9aaabddb-3636-4d2c-81cf-1dd0d8858414" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_9bc10e4e-9b43-4dea-b6e9-ceac44c31dfe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9aaabddb-3636-4d2c-81cf-1dd0d8858414" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_e721933d-cac3-480d-9476-6d276b70e7f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9aaabddb-3636-4d2c-81cf-1dd0d8858414" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_e721933d-cac3-480d-9476-6d276b70e7f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_576952d7-4a33-4734-91f3-579a57e8fc0b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9aaabddb-3636-4d2c-81cf-1dd0d8858414" xlink:to="loc_us-gaap_EmployeeStockOptionMember_576952d7-4a33-4734-91f3-579a57e8fc0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusAxis_84b72ee9-1c1b-41ec-a36f-e1255ce99712" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GranteeStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2bbff769-e703-4c69-ab04-e9549f97a123" xlink:to="loc_us-gaap_GranteeStatusAxis_84b72ee9-1c1b-41ec-a36f-e1255ce99712" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_84b72ee9-1c1b-41ec-a36f-e1255ce99712_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GranteeStatusAxis_84b72ee9-1c1b-41ec-a36f-e1255ce99712" xlink:to="loc_us-gaap_GranteeStatusDomain_84b72ee9-1c1b-41ec-a36f-e1255ce99712_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_2326d0b7-0549-4c5d-b888-9fe7609b292a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GranteeStatusAxis_84b72ee9-1c1b-41ec-a36f-e1255ce99712" xlink:to="loc_us-gaap_GranteeStatusDomain_2326d0b7-0549-4c5d-b888-9fe7609b292a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedPaymentArrangementEmployeeMember_a9f6b357-73d2-4b1b-a8a5-9f34912c8d0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedPaymentArrangementEmployeeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_2326d0b7-0549-4c5d-b888-9fe7609b292a" xlink:to="loc_us-gaap_ShareBasedPaymentArrangementEmployeeMember_a9f6b357-73d2-4b1b-a8a5-9f34912c8d0d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedPaymentArrangementNonemployeeMember_4da84e53-1fbb-45ea-9a68-e3af1811d680" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedPaymentArrangementNonemployeeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_2326d0b7-0549-4c5d-b888-9fe7609b292a" xlink:to="loc_us-gaap_ShareBasedPaymentArrangementNonemployeeMember_4da84e53-1fbb-45ea-9a68-e3af1811d680" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_b5d3f34a-a509-4739-a691-54f196f5138a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_b5d3f34a-a509-4739-a691-54f196f5138a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_78fc04aa-d24d-4b08-b0a0-239399141949" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_78fc04aa-d24d-4b08-b0a0-239399141949" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_06d9e44d-c747-4a39-b32d-d77de1268fe7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_06d9e44d-c747-4a39-b32d-d77de1268fe7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_4bf725af-7681-4b77-bd52-63f12b937df2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_4bf725af-7681-4b77-bd52-63f12b937df2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_cddd8c8b-fc60-4486-96c7-be37370bf4f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_cddd8c8b-fc60-4486-96c7-be37370bf4f4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee_2c6cf5d8-2db5-47cf-892a-d7ae1c49d182" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee_2c6cf5d8-2db5-47cf-892a-d7ae1c49d182" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_725bb45a-63bb-48b6-8492-ee40e62241ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_725bb45a-63bb-48b6-8492-ee40e62241ce" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_95956e52-0c59-4cf4-abfb-fe4d8ef23f37" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_95956e52-0c59-4cf4-abfb-fe4d8ef23f37" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_f5cd84f5-6b82-4ea6-8604-02af30f92870" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_f5cd84f5-6b82-4ea6-8604-02af30f92870" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_87714b5a-580a-42a2-b038-0056e8c2ef9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_333b2c0a-65c3-4f87-8ef4-8eb328ec8463" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_87714b5a-580a-42a2-b038-0056e8c2ef9f" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/STOCKBASEDCOMPENSATIONScheduleofNonvestedRestrictedSharesDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#STOCKBASEDCOMPENSATIONScheduleofNonvestedRestrictedSharesDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/STOCKBASEDCOMPENSATIONScheduleofNonvestedRestrictedSharesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ca7dffe-c769-4839-bbc6-aebbf2f05664" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1d8a92f6-8398-4664-b9c9-b2a2f3e8ce08" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ca7dffe-c769-4839-bbc6-aebbf2f05664" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1d8a92f6-8398-4664-b9c9-b2a2f3e8ce08" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_13d2919c-b847-4f0b-9120-a0566842d86c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1d8a92f6-8398-4664-b9c9-b2a2f3e8ce08" xlink:to="loc_us-gaap_AwardTypeAxis_13d2919c-b847-4f0b-9120-a0566842d86c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_13d2919c-b847-4f0b-9120-a0566842d86c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_13d2919c-b847-4f0b-9120-a0566842d86c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_13d2919c-b847-4f0b-9120-a0566842d86c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a31a4ad-8b7d-4c3b-a020-894cea4d1986" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_13d2919c-b847-4f0b-9120-a0566842d86c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a31a4ad-8b7d-4c3b-a020-894cea4d1986" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_e6072799-0e76-4a1c-b6be-df67b668feb4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a31a4ad-8b7d-4c3b-a020-894cea4d1986" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_e6072799-0e76-4a1c-b6be-df67b668feb4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_44e70b8f-7c13-4a5f-82f8-e6cac4c5b439" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ca7dffe-c769-4839-bbc6-aebbf2f05664" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_44e70b8f-7c13-4a5f-82f8-e6cac4c5b439" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_0375a160-fd58-45f0-9ea5-d1207280b1da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_44e70b8f-7c13-4a5f-82f8-e6cac4c5b439" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_0375a160-fd58-45f0-9ea5-d1207280b1da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_50662cee-c9cd-42f9-a97a-c216ff1cd303" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_44e70b8f-7c13-4a5f-82f8-e6cac4c5b439" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_50662cee-c9cd-42f9-a97a-c216ff1cd303" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_afd03ba7-229b-47ce-ae3b-5fece9ef196e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_44e70b8f-7c13-4a5f-82f8-e6cac4c5b439" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_afd03ba7-229b-47ce-ae3b-5fece9ef196e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_0d82bbe0-4a43-4d93-8454-f20a9bca9c7d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_44e70b8f-7c13-4a5f-82f8-e6cac4c5b439" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_0d82bbe0-4a43-4d93-8454-f20a9bca9c7d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_d4619eea-d32a-4409-bb9a-e22ed201a865" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_42c86f19-01eb-481a-9d6b-747f102ae80b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ca7dffe-c769-4839-bbc6-aebbf2f05664" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_42c86f19-01eb-481a-9d6b-747f102ae80b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ca3e14ae-86cf-49a1-98e7-388cae7cde62" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_42c86f19-01eb-481a-9d6b-747f102ae80b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ca3e14ae-86cf-49a1-98e7-388cae7cde62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_cc9740b6-c79a-4086-9131-422952023cfe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_42c86f19-01eb-481a-9d6b-747f102ae80b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_cc9740b6-c79a-4086-9131-422952023cfe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_a4256aa0-8fc7-4764-82f1-64907a2722b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_42c86f19-01eb-481a-9d6b-747f102ae80b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_a4256aa0-8fc7-4764-82f1-64907a2722b7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_025ab1e7-a169-4dd8-8250-303596e74b40" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_42c86f19-01eb-481a-9d6b-747f102ae80b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_025ab1e7-a169-4dd8-8250-303596e74b40" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_f32cf34b-6559-40c0-b3a0-fa65b7611dfe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/OTHERBENEFITPLANSDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#OTHERBENEFITPLANSDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/OTHERBENEFITPLANSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_88a3eb82-952d-476e-8810-4562689e7c80" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_88a3eb82-952d-476e-8810-4562689e7c80" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_43e09856-3dec-4af3-9210-fa909e23fe19" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_88a3eb82-952d-476e-8810-4562689e7c80" xlink:to="loc_us-gaap_AwardTypeAxis_43e09856-3dec-4af3-9210-fa909e23fe19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_43e09856-3dec-4af3-9210-fa909e23fe19_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_43e09856-3dec-4af3-9210-fa909e23fe19" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_43e09856-3dec-4af3-9210-fa909e23fe19_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bb1a1355-1fbd-40b0-bd1b-03afb6516428" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_43e09856-3dec-4af3-9210-fa909e23fe19" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bb1a1355-1fbd-40b0-bd1b-03afb6516428" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_24385a7c-f85c-4516-96e9-72d314acc3b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bb1a1355-1fbd-40b0-bd1b-03afb6516428" xlink:to="loc_us-gaap_EmployeeStockMember_24385a7c-f85c-4516-96e9-72d314acc3b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesDividendReinvestmentPlan_c00e46a4-6927-4f48-aa55-fefaed0a6794" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesDividendReinvestmentPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesDividendReinvestmentPlan_c00e46a4-6927-4f48-aa55-fefaed0a6794" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_9b0ee05f-31ea-46f1-9f91-7f494f8b2299" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_9b0ee05f-31ea-46f1-9f91-7f494f8b2299" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_NonQualifiedStockPurchasePlanSharesPurchasedDuringPeriod_217e4ca3-fb5b-4457-b853-0604812ecc4c" xlink:href="bafn-20251231.xsd#bafn_NonQualifiedStockPurchasePlanSharesPurchasedDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_bafn_NonQualifiedStockPurchasePlanSharesPurchasedDuringPeriod_217e4ca3-fb5b-4457-b853-0604812ecc4c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_NonQualifiedStockPurchasePlanSharesPurchasedDuringPeriodAveragePricePerShare_1dc16e8d-198d-4c74-ae13-1fd00dbf6926" xlink:href="bafn-20251231.xsd#bafn_NonQualifiedStockPurchasePlanSharesPurchasedDuringPeriodAveragePricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_bafn_NonQualifiedStockPurchasePlanSharesPurchasedDuringPeriodAveragePricePerShare_1dc16e8d-198d-4c74-ae13-1fd00dbf6926" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_NonQualifiedStockPurchasePlanSharesIssuedDuringPeriod_9dbe4c38-5a86-43d7-8e94-5e498411c6c8" xlink:href="bafn-20251231.xsd#bafn_NonQualifiedStockPurchasePlanSharesIssuedDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_bafn_NonQualifiedStockPurchasePlanSharesIssuedDuringPeriod_9dbe4c38-5a86-43d7-8e94-5e498411c6c8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_SupplementalUnemploymentBenefitsSalaryContinuationAnnualCompensationAmount_ff1e801f-4d75-4c23-a220-ec1957d80dcf" xlink:href="bafn-20251231.xsd#bafn_SupplementalUnemploymentBenefitsSalaryContinuationAnnualCompensationAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_bafn_SupplementalUnemploymentBenefitsSalaryContinuationAnnualCompensationAmount_ff1e801f-4d75-4c23-a220-ec1957d80dcf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_SupplementalUnemploymentBenefitsSalaryContinuationPeriod_05c59e35-e559-42d3-8152-08bf1261498a" xlink:href="bafn-20251231.xsd#bafn_SupplementalUnemploymentBenefitsSalaryContinuationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_bafn_SupplementalUnemploymentBenefitsSalaryContinuationPeriod_05c59e35-e559-42d3-8152-08bf1261498a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalUnemploymentBenefitsSalaryContinuation_1c4a95df-75f7-47a6-baa9-cd8d3b59295c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplementalUnemploymentBenefitsSalaryContinuation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_us-gaap_SupplementalUnemploymentBenefitsSalaryContinuation_1c4a95df-75f7-47a6-baa9-cd8d3b59295c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PostemploymentBenefitsPeriodExpense_fa12abce-57ad-4be1-ab71-22f823eab274" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PostemploymentBenefitsPeriodExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_us-gaap_PostemploymentBenefitsPeriodExpense_fa12abce-57ad-4be1-ab71-22f823eab274" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_DefinedContributionPlanEmployerContributionPercentOfEmployeesGrossPay_df7de72f-f20b-43ff-a97a-72106b027155" xlink:href="bafn-20251231.xsd#bafn_DefinedContributionPlanEmployerContributionPercentOfEmployeesGrossPay"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_bafn_DefinedContributionPlanEmployerContributionPercentOfEmployeesGrossPay_df7de72f-f20b-43ff-a97a-72106b027155" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized_6e45185b-7fb3-4f97-a260-632b8e4ca366" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanCostRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_us-gaap_DefinedContributionPlanCostRecognized_6e45185b-7fb3-4f97-a260-632b8e4ca366" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOwnershipPlanESOPNumberOfCommittedToBeReleasedShares_d8937e15-7e87-451d-8836-9494da05e237" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOwnershipPlanESOPNumberOfCommittedToBeReleasedShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_us-gaap_EmployeeStockOwnershipPlanESOPNumberOfCommittedToBeReleasedShares_d8937e15-7e87-451d-8836-9494da05e237" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOwnershipPlanESOPFairValueOfSharesSubjectToRepurchaseObligation_6187e739-7315-4c4a-95f4-04f04c9600ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOwnershipPlanESOPFairValueOfSharesSubjectToRepurchaseObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_us-gaap_EmployeeStockOwnershipPlanESOPFairValueOfSharesSubjectToRepurchaseObligation_6187e739-7315-4c4a-95f4-04f04c9600ec" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_EmployeeStockOwnershipPlanESOPPercentOfEmployersContributionVestForLaidOffParticipants_7f09d9a2-dd9c-4171-928a-14b346198488" xlink:href="bafn-20251231.xsd#bafn_EmployeeStockOwnershipPlanESOPPercentOfEmployersContributionVestForLaidOffParticipants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_bafn_EmployeeStockOwnershipPlanESOPPercentOfEmployersContributionVestForLaidOffParticipants_7f09d9a2-dd9c-4171-928a-14b346198488" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_EmployeeStockOwnershipPlanESOPRemainingIndebtednessOfOutstandingLoans_911ddc69-5866-4930-ab30-d2ee1f02c066" xlink:href="bafn-20251231.xsd#bafn_EmployeeStockOwnershipPlanESOPRemainingIndebtednessOfOutstandingLoans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_bafn_EmployeeStockOwnershipPlanESOPRemainingIndebtednessOfOutstandingLoans_911ddc69-5866-4930-ab30-d2ee1f02c066" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense_d746638e-8cad-42ee-9fee-0649e98d18ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10aaf469-935e-4647-9aa0-dc792c7705a2" xlink:to="loc_us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense_d746638e-8cad-42ee-9fee-0649e98d18ec" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/INCOMETAXESScheduleofCashTaxesPaidDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#INCOMETAXESScheduleofCashTaxesPaidDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/INCOMETAXESScheduleofCashTaxesPaidDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_019c11ac-acbe-7bf4-a718-b67e20c0cc9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxContingencyLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_019c11ac-acbe-7512-9e0b-0331ea1ce944" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxContingencyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_019c11ac-acbe-7bf4-a718-b67e20c0cc9b" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_019c11ac-acbe-7512-9e0b-0331ea1ce944" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_019c11ac-acbe-7f9b-8277-1655ea5b276c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_019c11ac-acbe-7512-9e0b-0331ea1ce944" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_019c11ac-acbe-7f9b-8277-1655ea5b276c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019c11ac-acbe-7f9b-8277-1655ea5b276c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019c11ac-acbe-7f9b-8277-1655ea5b276c" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019c11ac-acbe-7f9b-8277-1655ea5b276c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019c11ac-acbe-77f4-b920-fe797d8ab470" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019c11ac-acbe-7f9b-8277-1655ea5b276c" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019c11ac-acbe-77f4-b920-fe797d8ab470" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_019c11b8-0358-7236-a554-11117a6136a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019c11ac-acbe-77f4-b920-fe797d8ab470" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_019c11b8-0358-7236-a554-11117a6136a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_FL_019c11ac-acbe-7eec-ad9f-ca5587b50ee1" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_FL"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019c11b8-0358-7236-a554-11117a6136a8" xlink:to="loc_stpr_FL_019c11ac-acbe-7eec-ad9f-ca5587b50ee1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalTaxJurisdictionOtherMember_019c1a56-170b-7de5-868a-31b3e1a390ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalTaxJurisdictionOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019c11b8-0358-7236-a554-11117a6136a8" xlink:to="loc_us-gaap_StateAndLocalTaxJurisdictionOtherMember_019c1a56-170b-7de5-868a-31b3e1a390ed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNetAbstract_019cfd55-7fc4-7482-b0c2-89747934d2a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxesPaidNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_019c11ac-acbe-7bf4-a718-b67e20c0cc9b" xlink:to="loc_us-gaap_IncomeTaxesPaidNetAbstract_019cfd55-7fc4-7482-b0c2-89747934d2a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidFederalAfterRefundReceived_019c11ac-acbe-73a1-abed-c633754e795f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidFederalAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxesPaidNetAbstract_019cfd55-7fc4-7482-b0c2-89747934d2a2" xlink:to="loc_us-gaap_IncomeTaxPaidFederalAfterRefundReceived_019c11ac-acbe-73a1-abed-c633754e795f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived_019c11ac-acbe-7207-96a5-46c4e384e646" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxesPaidNetAbstract_019cfd55-7fc4-7482-b0c2-89747934d2a2" xlink:to="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived_019c11ac-acbe-7207-96a5-46c4e384e646" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_019c11ac-acbe-7c58-9194-3a2d4fee0720" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxesPaidNetAbstract_019cfd55-7fc4-7482-b0c2-89747934d2a2" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_019c11ac-acbe-7c58-9194-3a2d4fee0720" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/INCOMETAXESNarrativeDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#INCOMETAXESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/INCOMETAXESNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_af4673ee-eae5-4185-9ed5-328cf16840e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxContingencyLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_5afb74e7-d8c8-47f8-9ffa-01062b0a28e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxContingencyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_af4673ee-eae5-4185-9ed5-328cf16840e8" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_5afb74e7-d8c8-47f8-9ffa-01062b0a28e4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_70fe3073-43b3-460a-993e-6e7acf5a3671" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_5afb74e7-d8c8-47f8-9ffa-01062b0a28e4" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_70fe3073-43b3-460a-993e-6e7acf5a3671" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_70fe3073-43b3-460a-993e-6e7acf5a3671_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_70fe3073-43b3-460a-993e-6e7acf5a3671" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_70fe3073-43b3-460a-993e-6e7acf5a3671_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_d88d2792-598e-4f85-8fa0-224de4da1cd0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_70fe3073-43b3-460a-993e-6e7acf5a3671" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_d88d2792-598e-4f85-8fa0-224de4da1cd0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_1a38d70a-57e6-4fce-82e6-06d8cf72a3b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_d88d2792-598e-4f85-8fa0-224de4da1cd0" xlink:to="loc_us-gaap_DomesticCountryMember_1a38d70a-57e6-4fce-82e6-06d8cf72a3b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_b6ac368a-d356-4a4b-9ee5-cea0986aac10" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_d88d2792-598e-4f85-8fa0-224de4da1cd0" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_b6ac368a-d356-4a4b-9ee5-cea0986aac10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_c708810e-4bd2-4e6f-94f9-91d14f5f789d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_af4673ee-eae5-4185-9ed5-328cf16840e8" xlink:to="loc_us-gaap_OperatingLossCarryforwards_c708810e-4bd2-4e6f-94f9-91d14f5f789d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/RELATEDPARTYTRANSACTIONSNarrativeDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#RELATEDPARTYTRANSACTIONSNarrativeDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/RELATEDPARTYTRANSACTIONSNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_7d9fd451-3915-4e01-aebc-27d47fcabc3d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7a29062c-5a34-442a-aa0e-73f508882806" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_7d9fd451-3915-4e01-aebc-27d47fcabc3d" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7a29062c-5a34-442a-aa0e-73f508882806" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAxis_1d3cb820-a520-4bce-b577-fd0150699e8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7a29062c-5a34-442a-aa0e-73f508882806" xlink:to="loc_us-gaap_RelatedPartyTransactionAxis_1d3cb820-a520-4bce-b577-fd0150699e8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_1d3cb820-a520-4bce-b577-fd0150699e8b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_1d3cb820-a520-4bce-b577-fd0150699e8b" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_1d3cb820-a520-4bce-b577-fd0150699e8b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_b9ccc56b-bee1-4020-b6a7-b381d19f9723" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_1d3cb820-a520-4bce-b577-fd0150699e8b" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_b9ccc56b-bee1-4020-b6a7-b381d19f9723" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_RelatedPartyLeasingTransactionsMember_038000c1-328e-4d91-9d1e-73f60555f53e" xlink:href="bafn-20251231.xsd#bafn_RelatedPartyLeasingTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_b9ccc56b-bee1-4020-b6a7-b381d19f9723" xlink:to="loc_bafn_RelatedPartyLeasingTransactionsMember_038000c1-328e-4d91-9d1e-73f60555f53e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_RelatedPartyInsuranceTransactionsMember_499a3378-a220-4c7d-a0b9-1570902d699d" xlink:href="bafn-20251231.xsd#bafn_RelatedPartyInsuranceTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_b9ccc56b-bee1-4020-b6a7-b381d19f9723" xlink:to="loc_bafn_RelatedPartyInsuranceTransactionsMember_499a3378-a220-4c7d-a0b9-1570902d699d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0f836246-8e5d-4394-a06f-65e6697330dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7a29062c-5a34-442a-aa0e-73f508882806" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0f836246-8e5d-4394-a06f-65e6697330dc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_0f836246-8e5d-4394-a06f-65e6697330dc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0f836246-8e5d-4394-a06f-65e6697330dc" xlink:to="loc_us-gaap_RelatedPartyDomain_0f836246-8e5d-4394-a06f-65e6697330dc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_ebb660cb-2153-4d14-b420-207da105bec4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0f836246-8e5d-4394-a06f-65e6697330dc" xlink:to="loc_us-gaap_RelatedPartyDomain_ebb660cb-2153-4d14-b420-207da105bec4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_b81a74fd-8c45-4f88-bf1c-b3b27c21ba01" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_ebb660cb-2153-4d14-b420-207da105bec4" xlink:to="loc_us-gaap_RelatedPartyMember_b81a74fd-8c45-4f88-bf1c-b3b27c21ba01" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDepositLiabilities_bab2b502-97f2-4bd4-a422-c00a4a41fd6f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDepositLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_7d9fd451-3915-4e01-aebc-27d47fcabc3d" xlink:to="loc_us-gaap_RelatedPartyDepositLiabilities_bab2b502-97f2-4bd4-a422-c00a4a41fd6f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingCostsAndExpenses_74020662-8abb-47fa-808f-9ab3a71e6802" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingCostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_7d9fd451-3915-4e01-aebc-27d47fcabc3d" xlink:to="loc_us-gaap_OperatingCostsAndExpenses_74020662-8abb-47fa-808f-9ab3a71e6802" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/LOANCOMMITMENTSANDOTHERRELATEDACTIVITIESScheduleofFinancialInstrumentsWithOffBalanceSheetRiskDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#LOANCOMMITMENTSANDOTHERRELATEDACTIVITIESScheduleofFinancialInstrumentsWithOffBalanceSheetRiskDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/LOANCOMMITMENTSANDOTHERRELATEDACTIVITIESScheduleofFinancialInstrumentsWithOffBalanceSheetRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_58c47c8b-8efc-4a96-8c09-55afc699aa0c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_2c020872-0417-4f02-8efb-bad5d26a772d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_58c47c8b-8efc-4a96-8c09-55afc699aa0c" xlink:to="loc_us-gaap_OtherCommitmentsTable_2c020872-0417-4f02-8efb-bad5d26a772d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_f7e07c56-be33-4048-adf8-9f700342d776" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_2c020872-0417-4f02-8efb-bad5d26a772d" xlink:to="loc_us-gaap_FinancialInstrumentAxis_f7e07c56-be33-4048-adf8-9f700342d776" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f7e07c56-be33-4048-adf8-9f700342d776_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_f7e07c56-be33-4048-adf8-9f700342d776" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f7e07c56-be33-4048-adf8-9f700342d776_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_90553a1e-b002-4441-bd7e-2fd2b9c043d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_f7e07c56-be33-4048-adf8-9f700342d776" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_90553a1e-b002-4441-bd7e-2fd2b9c043d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnfundedLoanCommitmentMember_472ff51d-e7d8-4d9a-bbed-5fd89b6808ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnfundedLoanCommitmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_90553a1e-b002-4441-bd7e-2fd2b9c043d5" xlink:to="loc_us-gaap_UnfundedLoanCommitmentMember_472ff51d-e7d8-4d9a-bbed-5fd89b6808ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnusedLinesOfCreditMember_739bb066-39f5-4256-aed3-6430e8fda99c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnusedLinesOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_90553a1e-b002-4441-bd7e-2fd2b9c043d5" xlink:to="loc_us-gaap_UnusedLinesOfCreditMember_739bb066-39f5-4256-aed3-6430e8fda99c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandbyLettersOfCreditMember_719206d4-e8b4-419d-a00d-59bd5d429732" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StandbyLettersOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_90553a1e-b002-4441-bd7e-2fd2b9c043d5" xlink:to="loc_us-gaap_StandbyLettersOfCreditMember_719206d4-e8b4-419d-a00d-59bd5d429732" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability_46b8dd36-767b-4ae7-8d33-4409a99c7980" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_58c47c8b-8efc-4a96-8c09-55afc699aa0c" xlink:to="loc_us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability_46b8dd36-767b-4ae7-8d33-4409a99c7980" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/LOANCOMMITMENTSANDOTHERRELATEDACTIVITIESNarrativeDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#LOANCOMMITMENTSANDOTHERRELATEDACTIVITIESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/LOANCOMMITMENTSANDOTHERRELATEDACTIVITIESNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_7c59fd2a-f3fb-4649-a9bb-fa2b8eb0d5f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_e832a1dc-2ba8-4860-8a87-0871d62cb033" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7c59fd2a-f3fb-4649-a9bb-fa2b8eb0d5f0" xlink:to="loc_us-gaap_OtherCommitmentsTable_e832a1dc-2ba8-4860-8a87-0871d62cb033" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsAxis_a4fdd489-45a8-4737-953a-5e62bfbac97d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_e832a1dc-2ba8-4860-8a87-0871d62cb033" xlink:to="loc_us-gaap_OtherCommitmentsAxis_a4fdd489-45a8-4737-953a-5e62bfbac97d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_a4fdd489-45a8-4737-953a-5e62bfbac97d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherCommitmentsAxis_a4fdd489-45a8-4737-953a-5e62bfbac97d" xlink:to="loc_us-gaap_OtherCommitmentsDomain_a4fdd489-45a8-4737-953a-5e62bfbac97d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_2beef4e4-3d09-49e0-978d-7270d261fdb3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherCommitmentsAxis_a4fdd489-45a8-4737-953a-5e62bfbac97d" xlink:to="loc_us-gaap_OtherCommitmentsDomain_2beef4e4-3d09-49e0-978d-7270d261fdb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnfundedLoanCommitmentMember_72931957-7a5c-4ec2-a240-ad2528930426" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnfundedLoanCommitmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_2beef4e4-3d09-49e0-978d-7270d261fdb3" xlink:to="loc_us-gaap_UnfundedLoanCommitmentMember_72931957-7a5c-4ec2-a240-ad2528930426" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_482b0226-3284-4cb5-b7db-6011eea15066" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_e832a1dc-2ba8-4860-8a87-0871d62cb033" xlink:to="loc_us-gaap_FinancialInstrumentAxis_482b0226-3284-4cb5-b7db-6011eea15066" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_482b0226-3284-4cb5-b7db-6011eea15066_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_482b0226-3284-4cb5-b7db-6011eea15066" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_482b0226-3284-4cb5-b7db-6011eea15066_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_88a7f7ce-51c5-4da7-b476-01b81c2af656" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_482b0226-3284-4cb5-b7db-6011eea15066" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_88a7f7ce-51c5-4da7-b476-01b81c2af656" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnfundedLoanCommitmentMember_554c031f-5893-405f-a8dc-90e74e411421" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnfundedLoanCommitmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_88a7f7ce-51c5-4da7-b476-01b81c2af656" xlink:to="loc_us-gaap_UnfundedLoanCommitmentMember_554c031f-5893-405f-a8dc-90e74e411421" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_UnfundedLoanCommitmentsMaturityTerm_eb08ffdc-0de5-40ba-a775-bb21a0eba515" xlink:href="bafn-20251231.xsd#bafn_UnfundedLoanCommitmentsMaturityTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7c59fd2a-f3fb-4649-a9bb-fa2b8eb0d5f0" xlink:to="loc_bafn_UnfundedLoanCommitmentsMaturityTerm_eb08ffdc-0de5-40ba-a775-bb21a0eba515" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffBalanceSheetCreditLossLiability_0cb2a2af-1041-4ef0-aa2e-5e43c432803a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OffBalanceSheetCreditLossLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_7c59fd2a-f3fb-4649-a9bb-fa2b8eb0d5f0" xlink:to="loc_us-gaap_OffBalanceSheetCreditLossLiability_0cb2a2af-1041-4ef0-aa2e-5e43c432803a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/EARNINGSPERCOMMONSHAREScheduleofAntidilutiveSecuritiesExcludedfromCalculationofWeightedAverageSharesOutstandingDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#EARNINGSPERCOMMONSHAREScheduleofAntidilutiveSecuritiesExcludedfromCalculationofWeightedAverageSharesOutstandingDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/EARNINGSPERCOMMONSHAREScheduleofAntidilutiveSecuritiesExcludedfromCalculationofWeightedAverageSharesOutstandingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_79bf7247-9f31-4f1f-aef3-beaeb8190473" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_53860d7a-958e-4e54-865a-661330ccd055" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_79bf7247-9f31-4f1f-aef3-beaeb8190473" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_53860d7a-958e-4e54-865a-661330ccd055" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6c9ff841-46c8-46e1-9418-b4e4d2612dea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_53860d7a-958e-4e54-865a-661330ccd055" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6c9ff841-46c8-46e1-9418-b4e4d2612dea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6c9ff841-46c8-46e1-9418-b4e4d2612dea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6c9ff841-46c8-46e1-9418-b4e4d2612dea" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6c9ff841-46c8-46e1-9418-b4e4d2612dea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_0528ed90-826a-4367-a52f-d35e771a916e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6c9ff841-46c8-46e1-9418-b4e4d2612dea" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_0528ed90-826a-4367-a52f-d35e771a916e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_1d139ffb-5eec-447c-9d44-635510ecfa4e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_0528ed90-826a-4367-a52f-d35e771a916e" xlink:to="loc_us-gaap_EmployeeStockOptionMember_1d139ffb-5eec-447c-9d44-635510ecfa4e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConvertibleSeriesBPreferredStockMember_6b74db15-11b4-40c9-b055-859762cb84ef" xlink:href="bafn-20251231.xsd#bafn_ConvertibleSeriesBPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_0528ed90-826a-4367-a52f-d35e771a916e" xlink:to="loc_bafn_ConvertibleSeriesBPreferredStockMember_6b74db15-11b4-40c9-b055-859762cb84ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ConvertibleSeriesCPreferredStockMember_13de4508-47c1-4d6e-8534-0ef7d20a7d2d" xlink:href="bafn-20251231.xsd#bafn_ConvertibleSeriesCPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_0528ed90-826a-4367-a52f-d35e771a916e" xlink:to="loc_bafn_ConvertibleSeriesCPreferredStockMember_13de4508-47c1-4d6e-8534-0ef7d20a7d2d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_eeed9def-2bdf-48e3-9a5e-d3679e3e56ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_79bf7247-9f31-4f1f-aef3-beaeb8190473" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_eeed9def-2bdf-48e3-9a5e-d3679e3e56ea" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/RESTRUCTURECHARGESDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#RESTRUCTURECHARGESDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/RESTRUCTURECHARGESDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_1f58b94f-ba86-443a-b19e-d2c661b58a21" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_b0bba560-c4fd-4e96-bcc6-9c1dc0f17e88" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_1f58b94f-ba86-443a-b19e-d2c661b58a21" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_b0bba560-c4fd-4e96-bcc6-9c1dc0f17e88" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_72648705-1603-42a3-9b61-97fa67e093ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_b0bba560-c4fd-4e96-bcc6-9c1dc0f17e88" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_72648705-1603-42a3-9b61-97fa67e093ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_72648705-1603-42a3-9b61-97fa67e093ea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_72648705-1603-42a3-9b61-97fa67e093ea" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_72648705-1603-42a3-9b61-97fa67e093ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_8158dac3-5abb-4e05-b7f1-49576bc2a722" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_72648705-1603-42a3-9b61-97fa67e093ea" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_8158dac3-5abb-4e05-b7f1-49576bc2a722" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_146d8e10-6f21-45f9-a56a-cf376ed13606" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_8158dac3-5abb-4e05-b7f1-49576bc2a722" xlink:to="loc_us-gaap_EmployeeSeveranceMember_146d8e10-6f21-45f9-a56a-cf376ed13606" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ImpairedAssetsMember_f394db6a-084f-4733-a405-f455af7e863d" xlink:href="bafn-20251231.xsd#bafn_ImpairedAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_8158dac3-5abb-4e05-b7f1-49576bc2a722" xlink:to="loc_bafn_ImpairedAssetsMember_f394db6a-084f-4733-a405-f455af7e863d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_BrokerCostsMember_8639c3ca-0b79-4233-a84e-4027d2a71912" xlink:href="bafn-20251231.xsd#bafn_BrokerCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_8158dac3-5abb-4e05-b7f1-49576bc2a722" xlink:to="loc_bafn_BrokerCostsMember_8639c3ca-0b79-4233-a84e-4027d2a71912" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRestructuringMember_a69cc0f2-f7ef-4de7-8e88-84e5e33d710e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherRestructuringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_8158dac3-5abb-4e05-b7f1-49576bc2a722" xlink:to="loc_us-gaap_OtherRestructuringMember_a69cc0f2-f7ef-4de7-8e88-84e5e33d710e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_7bf6398d-63d8-41e9-9089-e41bcb57895d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_1f58b94f-ba86-443a-b19e-d2c661b58a21" xlink:to="loc_us-gaap_RestructuringCharges_7bf6398d-63d8-41e9-9089-e41bcb57895d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_019b0cc2-0ac5-767b-b933-cf689161adc4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_1f58b94f-ba86-443a-b19e-d2c661b58a21" xlink:to="loc_us-gaap_RestructuringReserve_019b0cc2-0ac5-767b-b933-cf689161adc4" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/PARENTCOMPANYONLYFINANCIALINFORMATIONScheduleofBalanceSheetDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#PARENTCOMPANYONLYFINANCIALINFORMATIONScheduleofBalanceSheetDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/PARENTCOMPANYONLYFINANCIALINFORMATIONScheduleofBalanceSheetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_srt_CondensedBalanceSheetStatementsCaptionsLineItems_947e9e50-3f46-47a8-9326-659700302371" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CondensedBalanceSheetStatementsCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CondensedBalanceSheetStatementTable_4cc743c8-d975-4e4b-b305-8c255a9c1bb6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CondensedBalanceSheetStatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_CondensedBalanceSheetStatementsCaptionsLineItems_947e9e50-3f46-47a8-9326-659700302371" xlink:to="loc_srt_CondensedBalanceSheetStatementTable_4cc743c8-d975-4e4b-b305-8c255a9c1bb6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_da10aaec-c963-4377-9d10-f4564026c8c7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_CondensedBalanceSheetStatementTable_4cc743c8-d975-4e4b-b305-8c255a9c1bb6" xlink:to="loc_srt_ConsolidatedEntitiesAxis_da10aaec-c963-4377-9d10-f4564026c8c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_da10aaec-c963-4377-9d10-f4564026c8c7_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_da10aaec-c963-4377-9d10-f4564026c8c7" xlink:to="loc_srt_ConsolidatedEntitiesDomain_da10aaec-c963-4377-9d10-f4564026c8c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_649878fb-0750-4a9d-bef6-d0952b70b10a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_da10aaec-c963-4377-9d10-f4564026c8c7" xlink:to="loc_srt_ConsolidatedEntitiesDomain_649878fb-0750-4a9d-bef6-d0952b70b10a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ParentCompanyMember_c3818e76-7c46-4234-ae05-daddaf5e7473" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ParentCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_649878fb-0750-4a9d-bef6-d0952b70b10a" xlink:to="loc_srt_ParentCompanyMember_c3818e76-7c46-4234-ae05-daddaf5e7473" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_c6378072-5bf0-4a1d-9758-79a0961eba86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_CondensedBalanceSheetStatementTable_4cc743c8-d975-4e4b-b305-8c255a9c1bb6" xlink:to="loc_us-gaap_StatementClassOfStockAxis_c6378072-5bf0-4a1d-9758-79a0961eba86" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_c6378072-5bf0-4a1d-9758-79a0961eba86_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_c6378072-5bf0-4a1d-9758-79a0961eba86" xlink:to="loc_us-gaap_ClassOfStockDomain_c6378072-5bf0-4a1d-9758-79a0961eba86_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_9590e623-0991-4701-ba4f-fd76310532b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_c6378072-5bf0-4a1d-9758-79a0961eba86" xlink:to="loc_us-gaap_ClassOfStockDomain_9590e623-0991-4701-ba4f-fd76310532b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_886354d8-6da9-4da1-8756-d1bb7859d637" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_9590e623-0991-4701-ba4f-fd76310532b8" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_886354d8-6da9-4da1-8756-d1bb7859d637" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesBPreferredStockMember_76b65e49-6ac3-4414-b32d-05c6a1095fef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesBPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_9590e623-0991-4701-ba4f-fd76310532b8" xlink:to="loc_us-gaap_SeriesBPreferredStockMember_76b65e49-6ac3-4414-b32d-05c6a1095fef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesCPreferredStockMember_6344b152-18ed-4b78-8e42-38e9ef089ef2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesCPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_9590e623-0991-4701-ba4f-fd76310532b8" xlink:to="loc_us-gaap_SeriesCPreferredStockMember_6344b152-18ed-4b78-8e42-38e9ef089ef2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_4bcbae83-d390-418a-b1ca-8406dbec23ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedBalanceSheetStatementsCaptionsLineItems_947e9e50-3f46-47a8-9326-659700302371" xlink:to="loc_us-gaap_AssetsAbstract_4bcbae83-d390-418a-b1ca-8406dbec23ab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_CashOnDepositWithSubsidiary_43f9215b-9218-463a-bdbf-2459009b95a0" xlink:href="bafn-20251231.xsd#bafn_CashOnDepositWithSubsidiary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_4bcbae83-d390-418a-b1ca-8406dbec23ab" xlink:to="loc_bafn_CashOnDepositWithSubsidiary_43f9215b-9218-463a-bdbf-2459009b95a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_ed2ff53a-ce27-4895-a532-0044dcdcce9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_4bcbae83-d390-418a-b1ca-8406dbec23ab" xlink:to="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_ed2ff53a-ce27-4895-a532-0044dcdcce9f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_7c071047-ecbe-42e4-9ec4-7f94c1c60bdd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_4bcbae83-d390-418a-b1ca-8406dbec23ab" xlink:to="loc_us-gaap_OtherAssets_7c071047-ecbe-42e4-9ec4-7f94c1c60bdd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_92bfd8fb-cdbf-4be6-9ecb-665eb158929b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_4bcbae83-d390-418a-b1ca-8406dbec23ab" xlink:to="loc_us-gaap_Assets_92bfd8fb-cdbf-4be6-9ecb-665eb158929b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract_ef1acfbd-ada6-4571-a9cc-1e19b5109da0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedBalanceSheetStatementsCaptionsLineItems_947e9e50-3f46-47a8-9326-659700302371" xlink:to="loc_us-gaap_LiabilitiesAbstract_ef1acfbd-ada6-4571-a9cc-1e19b5109da0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedDebt_a45442a7-f98e-4569-aa09-073f2f2788f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubordinatedDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_ef1acfbd-ada6-4571-a9cc-1e19b5109da0" xlink:to="loc_us-gaap_SubordinatedDebt_a45442a7-f98e-4569-aa09-073f2f2788f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayable_f74ff19d-a509-409f-aa9a-f9803a4d0eee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NotesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_ef1acfbd-ada6-4571-a9cc-1e19b5109da0" xlink:to="loc_us-gaap_NotesPayable_f74ff19d-a509-409f-aa9a-f9803a4d0eee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrentAndNoncurrent_42c1d336-bcaf-416d-a14a-2aa9693ce89d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_ef1acfbd-ada6-4571-a9cc-1e19b5109da0" xlink:to="loc_us-gaap_InterestPayableCurrentAndNoncurrent_42c1d336-bcaf-416d-a14a-2aa9693ce89d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_050484ad-3f7f-44ed-9600-a5d91a446aa9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_ef1acfbd-ada6-4571-a9cc-1e19b5109da0" xlink:to="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_050484ad-3f7f-44ed-9600-a5d91a446aa9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_29063add-28ce-4274-8d4c-dbbad98347c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_ef1acfbd-ada6-4571-a9cc-1e19b5109da0" xlink:to="loc_us-gaap_Liabilities_29063add-28ce-4274-8d4c-dbbad98347c9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_13cf6ff1-17ba-4a24-9f06-de97daa193c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedBalanceSheetStatementsCaptionsLineItems_947e9e50-3f46-47a8-9326-659700302371" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_13cf6ff1-17ba-4a24-9f06-de97daa193c8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_5b7a9e7c-543c-4199-aac7-ac24ff3121d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_13cf6ff1-17ba-4a24-9f06-de97daa193c8" xlink:to="loc_us-gaap_PreferredStockValue_5b7a9e7c-543c-4199-aac7-ac24ff3121d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStocksIncludingAdditionalPaidInCapital_d502c3fd-85a8-46f6-ae22-97bbc72c802c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStocksIncludingAdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_13cf6ff1-17ba-4a24-9f06-de97daa193c8" xlink:to="loc_us-gaap_CommonStocksIncludingAdditionalPaidInCapital_d502c3fd-85a8-46f6-ae22-97bbc72c802c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_beb9e23f-9671-4cde-bbaf-59528c666df7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_13cf6ff1-17ba-4a24-9f06-de97daa193c8" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_beb9e23f-9671-4cde-bbaf-59528c666df7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationEquity_4de5492d-853a-4cda-afdc-842f6b71f410" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_13cf6ff1-17ba-4a24-9f06-de97daa193c8" xlink:to="loc_us-gaap_DeferredCompensationEquity_4de5492d-853a-4cda-afdc-842f6b71f410" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_866e9de0-e95b-4072-a097-71d1174d5d1b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_13cf6ff1-17ba-4a24-9f06-de97daa193c8" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_866e9de0-e95b-4072-a097-71d1174d5d1b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_018bdf03-f356-420e-b16c-17af41b742d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_13cf6ff1-17ba-4a24-9f06-de97daa193c8" xlink:to="loc_us-gaap_StockholdersEquity_018bdf03-f356-420e-b16c-17af41b742d7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_cbc19c2f-cafc-487c-a389-b55db8e67114" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedBalanceSheetStatementsCaptionsLineItems_947e9e50-3f46-47a8-9326-659700302371" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_cbc19c2f-cafc-487c-a389-b55db8e67114" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_BalanceSheetParentheticalInformationAbstract_a5c53ff3-0f4e-441b-bf8d-0d5442a6bb01" xlink:href="bafn-20251231.xsd#bafn_BalanceSheetParentheticalInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedBalanceSheetStatementsCaptionsLineItems_947e9e50-3f46-47a8-9326-659700302371" xlink:to="loc_bafn_BalanceSheetParentheticalInformationAbstract_a5c53ff3-0f4e-441b-bf8d-0d5442a6bb01" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_16817211-942f-4564-9c0f-c3b62f4083f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_BalanceSheetParentheticalInformationAbstract_a5c53ff3-0f4e-441b-bf8d-0d5442a6bb01" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_16817211-942f-4564-9c0f-c3b62f4083f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_3381d2d3-1c87-4886-a0c8-5bec0f3c5c4b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_BalanceSheetParentheticalInformationAbstract_a5c53ff3-0f4e-441b-bf8d-0d5442a6bb01" xlink:to="loc_us-gaap_PreferredStockSharesIssued_3381d2d3-1c87-4886-a0c8-5bec0f3c5c4b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_0baefd54-249f-4d3d-aa0f-583971f62f83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_BalanceSheetParentheticalInformationAbstract_a5c53ff3-0f4e-441b-bf8d-0d5442a6bb01" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_0baefd54-249f-4d3d-aa0f-583971f62f83" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockLiquidationPreferenceValue_06b9855c-ea5e-4ac1-bfb6-9c5649d38295" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockLiquidationPreferenceValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_BalanceSheetParentheticalInformationAbstract_a5c53ff3-0f4e-441b-bf8d-0d5442a6bb01" xlink:to="loc_us-gaap_PreferredStockLiquidationPreferenceValue_06b9855c-ea5e-4ac1-bfb6-9c5649d38295" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_4c6c93ea-8b8e-403c-9a96-a3a801fc43b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_BalanceSheetParentheticalInformationAbstract_a5c53ff3-0f4e-441b-bf8d-0d5442a6bb01" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_4c6c93ea-8b8e-403c-9a96-a3a801fc43b9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_417b6157-fdbc-4e6b-a48e-989d9d2650d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_BalanceSheetParentheticalInformationAbstract_a5c53ff3-0f4e-441b-bf8d-0d5442a6bb01" xlink:to="loc_us-gaap_CommonStockSharesIssued_417b6157-fdbc-4e6b-a48e-989d9d2650d5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_bacc6fa4-f92d-484b-9323-a6cca3726af4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_BalanceSheetParentheticalInformationAbstract_a5c53ff3-0f4e-441b-bf8d-0d5442a6bb01" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_bacc6fa4-f92d-484b-9323-a6cca3726af4" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/PARENTCOMPANYONLYFINANCIALINFORMATIONScheduleofIncomeStatementDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#PARENTCOMPANYONLYFINANCIALINFORMATIONScheduleofIncomeStatementDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/PARENTCOMPANYONLYFINANCIALINFORMATIONScheduleofIncomeStatementDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_srt_CondensedIncomeStatementsCaptionsLineItems_7cfc5622-8531-4855-898d-c0edcb0ef73f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CondensedIncomeStatementsCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CondensedIncomeStatementTable_b4d1fb5b-41cf-4213-9198-8ae85631a9e0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CondensedIncomeStatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_CondensedIncomeStatementsCaptionsLineItems_7cfc5622-8531-4855-898d-c0edcb0ef73f" xlink:to="loc_srt_CondensedIncomeStatementTable_b4d1fb5b-41cf-4213-9198-8ae85631a9e0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_1b376869-d117-4bb7-9672-bd881a13ad26" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_CondensedIncomeStatementTable_b4d1fb5b-41cf-4213-9198-8ae85631a9e0" xlink:to="loc_srt_ConsolidatedEntitiesAxis_1b376869-d117-4bb7-9672-bd881a13ad26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_1b376869-d117-4bb7-9672-bd881a13ad26_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_1b376869-d117-4bb7-9672-bd881a13ad26" xlink:to="loc_srt_ConsolidatedEntitiesDomain_1b376869-d117-4bb7-9672-bd881a13ad26_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_06e0b1d9-707e-4039-aaa3-b373aee213b7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_1b376869-d117-4bb7-9672-bd881a13ad26" xlink:to="loc_srt_ConsolidatedEntitiesDomain_06e0b1d9-707e-4039-aaa3-b373aee213b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ParentCompanyMember_c20d3afd-e6a5-4d6c-b96a-519daa065a87" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ParentCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_06e0b1d9-707e-4039-aaa3-b373aee213b7" xlink:to="loc_srt_ParentCompanyMember_c20d3afd-e6a5-4d6c-b96a-519daa065a87" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_e384d21f-a4ce-45a2-a38d-815a2657ceb9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedIncomeStatementsCaptionsLineItems_7cfc5622-8531-4855-898d-c0edcb0ef73f" xlink:to="loc_us-gaap_RevenuesAbstract_e384d21f-a4ce-45a2-a38d-815a2657ceb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_DividendIncomeFromSubsidiary_1741548d-f022-4fa4-a13b-7a719539c637" xlink:href="bafn-20251231.xsd#bafn_DividendIncomeFromSubsidiary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_e384d21f-a4ce-45a2-a38d-815a2657ceb9" xlink:to="loc_bafn_DividendIncomeFromSubsidiary_1741548d-f022-4fa4-a13b-7a719539c637" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ExpenseAbstract_4cc61e84-25ba-47aa-bddf-7f77da8d9619" xlink:href="bafn-20251231.xsd#bafn_ExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedIncomeStatementsCaptionsLineItems_7cfc5622-8531-4855-898d-c0edcb0ef73f" xlink:to="loc_bafn_ExpenseAbstract_4cc61e84-25ba-47aa-bddf-7f77da8d9619" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_132d3688-dcce-4506-92ac-9637e3973f9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_ExpenseAbstract_4cc61e84-25ba-47aa-bddf-7f77da8d9619" xlink:to="loc_us-gaap_InterestExpense_132d3688-dcce-4506-92ac-9637e3973f9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherExpenses_d6584ba1-e0f2-4bc3-a3b3-6ff971cbcde5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_ExpenseAbstract_4cc61e84-25ba-47aa-bddf-7f77da8d9619" xlink:to="loc_us-gaap_OtherExpenses_d6584ba1-e0f2-4bc3-a3b3-6ff971cbcde5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_OperatingAndInterestExpense_3dcc9a78-ba7a-4e2f-8d1a-2666345dc2ac" xlink:href="bafn-20251231.xsd#bafn_OperatingAndInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_ExpenseAbstract_4cc61e84-25ba-47aa-bddf-7f77da8d9619" xlink:to="loc_bafn_OperatingAndInterestExpense_3dcc9a78-ba7a-4e2f-8d1a-2666345dc2ac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_IncomeLossFromContinuingOperationsBeforeIncomeTaxesAndIncomeLossFromSubsidiary_a3c24cb6-d2a3-4db7-affa-8fe51f7c9be7" xlink:href="bafn-20251231.xsd#bafn_IncomeLossFromContinuingOperationsBeforeIncomeTaxesAndIncomeLossFromSubsidiary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_ExpenseAbstract_4cc61e84-25ba-47aa-bddf-7f77da8d9619" xlink:to="loc_bafn_IncomeLossFromContinuingOperationsBeforeIncomeTaxesAndIncomeLossFromSubsidiary_a3c24cb6-d2a3-4db7-affa-8fe51f7c9be7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_bd86c037-2c2e-46e4-a0be-c472756454de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_ExpenseAbstract_4cc61e84-25ba-47aa-bddf-7f77da8d9619" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_bd86c037-2c2e-46e4-a0be-c472756454de" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_IncomeLossBeforeIncomeLossFromSubsidiaries_4fdffadf-7e01-41f8-9e0d-503ae83e5544" xlink:href="bafn-20251231.xsd#bafn_IncomeLossBeforeIncomeLossFromSubsidiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_ExpenseAbstract_4cc61e84-25ba-47aa-bddf-7f77da8d9619" xlink:to="loc_bafn_IncomeLossBeforeIncomeLossFromSubsidiaries_4fdffadf-7e01-41f8-9e0d-503ae83e5544" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromSubsidiariesNetOfTax_f4f14011-1f84-414a-a926-69931895e97b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromSubsidiariesNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_ExpenseAbstract_4cc61e84-25ba-47aa-bddf-7f77da8d9619" xlink:to="loc_us-gaap_IncomeLossFromSubsidiariesNetOfTax_f4f14011-1f84-414a-a926-69931895e97b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_05a71a8d-f720-43e4-abf2-2f7f0e83b9c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bafn_ExpenseAbstract_4cc61e84-25ba-47aa-bddf-7f77da8d9619" xlink:to="loc_us-gaap_NetIncomeLoss_05a71a8d-f720-43e4-abf2-2f7f0e83b9c6" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://bayfirstfinancial.com/role/PARENTCOMPANYONLYFINANCIALINFORMATIONScheduleofCashFlowStatementDetails" xlink:type="simple" xlink:href="bafn-20251231.xsd#PARENTCOMPANYONLYFINANCIALINFORMATIONScheduleofCashFlowStatementDetails"/>
  <link:definitionLink xlink:role="http://bayfirstfinancial.com/role/PARENTCOMPANYONLYFINANCIALINFORMATIONScheduleofCashFlowStatementDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_srt_CondensedCashFlowStatementsCaptionsLineItems_b48e6e70-febd-4ac9-a150-45d71532a7c7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CondensedCashFlowStatementsCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CondensedCashFlowStatementTable_af43ab17-0ad1-4daf-a6b2-859b93431e6a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CondensedCashFlowStatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_CondensedCashFlowStatementsCaptionsLineItems_b48e6e70-febd-4ac9-a150-45d71532a7c7" xlink:to="loc_srt_CondensedCashFlowStatementTable_af43ab17-0ad1-4daf-a6b2-859b93431e6a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_9513d85c-de87-4a50-868a-92cf889119a3" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_CondensedCashFlowStatementTable_af43ab17-0ad1-4daf-a6b2-859b93431e6a" xlink:to="loc_srt_ConsolidatedEntitiesAxis_9513d85c-de87-4a50-868a-92cf889119a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_9513d85c-de87-4a50-868a-92cf889119a3_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_9513d85c-de87-4a50-868a-92cf889119a3" xlink:to="loc_srt_ConsolidatedEntitiesDomain_9513d85c-de87-4a50-868a-92cf889119a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_e623eb10-3712-4347-b724-82c53351ab71" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_9513d85c-de87-4a50-868a-92cf889119a3" xlink:to="loc_srt_ConsolidatedEntitiesDomain_e623eb10-3712-4347-b724-82c53351ab71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ParentCompanyMember_ba0f6b1b-bce7-424a-a28f-6bc3647ffc37" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ParentCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_e623eb10-3712-4347-b724-82c53351ab71" xlink:to="loc_srt_ParentCompanyMember_ba0f6b1b-bce7-424a-a28f-6bc3647ffc37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_e0b42bad-f84a-44f1-aa4d-d9f772f9e76e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedCashFlowStatementsCaptionsLineItems_b48e6e70-febd-4ac9-a150-45d71532a7c7" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_e0b42bad-f84a-44f1-aa4d-d9f772f9e76e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_b9961752-d3a0-4136-824f-ba7ba2f41d93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_e0b42bad-f84a-44f1-aa4d-d9f772f9e76e" xlink:to="loc_us-gaap_NetIncomeLoss_b9961752-d3a0-4136-824f-ba7ba2f41d93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_dddaf2ab-3f3b-4a1c-b343-939ef065e92e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_e0b42bad-f84a-44f1-aa4d-d9f772f9e76e" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_dddaf2ab-3f3b-4a1c-b343-939ef065e92e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromSubsidiariesNetOfTax_41849d8f-8320-48ca-9093-e1b31296feb3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromSubsidiariesNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_dddaf2ab-3f3b-4a1c-b343-939ef065e92e" xlink:to="loc_us-gaap_IncomeLossFromSubsidiariesNetOfTax_41849d8f-8320-48ca-9093-e1b31296feb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_1bb5fe49-e4d4-42a1-96f5-d58072b1c7ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfFinancingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_dddaf2ab-3f3b-4a1c-b343-939ef065e92e" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_1bb5fe49-e4d4-42a1-96f5-d58072b1c7ff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingAssets_669c48f6-6eee-4339-923e-87f2d96470e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_dddaf2ab-3f3b-4a1c-b343-939ef065e92e" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingAssets_669c48f6-6eee-4339-923e-87f2d96470e6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_IncreaseDecreaseInInterestPayableNetAndOtherOperatingLiabilities_04dd957b-c611-4d9e-a6b8-c3da26b0ffeb" xlink:href="bafn-20251231.xsd#bafn_IncreaseDecreaseInInterestPayableNetAndOtherOperatingLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_dddaf2ab-3f3b-4a1c-b343-939ef065e92e" xlink:to="loc_bafn_IncreaseDecreaseInInterestPayableNetAndOtherOperatingLiabilities_04dd957b-c611-4d9e-a6b8-c3da26b0ffeb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_6944c01f-4081-4b10-88ec-625358cb6dad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_e0b42bad-f84a-44f1-aa4d-d9f772f9e76e" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_6944c01f-4081-4b10-88ec-625358cb6dad" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CondensedCashFlowStatementsCaptionsLineItems_b48e6e70-febd-4ac9-a150-45d71532a7c7" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_ProceedsFormNetIncreaseOfLoansToBankSubsidiary_222a125f-c99a-496d-9c90-d2045be95ff0" xlink:href="bafn-20251231.xsd#bafn_ProceedsFormNetIncreaseOfLoansToBankSubsidiary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:to="loc_bafn_ProceedsFormNetIncreaseOfLoansToBankSubsidiary_222a125f-c99a-496d-9c90-d2045be95ff0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfNotesPayable_15772930-ae94-4fa8-8a09-a3692da6c5fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfNotesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:to="loc_us-gaap_RepaymentsOfNotesPayable_15772930-ae94-4fa8-8a09-a3692da6c5fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_2fbbe80a-5cfe-4dfd-b6e3-bb005d733bed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_2fbbe80a-5cfe-4dfd-b6e3-bb005d733bed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_dc9425c6-b96b-47f8-9f8f-274cf0106440" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_dc9425c6-b96b-47f8-9f8f-274cf0106440" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_PaymentsForUnearnedESOPShares_2ac169e2-066c-4585-8c51-a34d05c87dab" xlink:href="bafn-20251231.xsd#bafn_PaymentsForUnearnedESOPShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:to="loc_bafn_PaymentsForUnearnedESOPShares_2ac169e2-066c-4585-8c51-a34d05c87dab" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsCommonStock_05fd4dca-3dcf-409d-8444-0ac7602811cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:to="loc_us-gaap_PaymentsOfDividendsCommonStock_05fd4dca-3dcf-409d-8444-0ac7602811cb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock_b65eae8a-0280-43b5-8775-1152826d12ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:to="loc_us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock_b65eae8a-0280-43b5-8775-1152826d12ca" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_8ebbef68-a876-4ae8-a312-5fcff6b4410d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_8ebbef68-a876-4ae8-a312-5fcff6b4410d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_d83bcbe6-98e8-483a-9241-8fec31b6aa16" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_d83bcbe6-98e8-483a-9241-8fec31b6aa16" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_e4991011-794b-45f3-8e69-0c0c11b243e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_7fdbe658-7b50-49f8-9710-3d450ca5afdd" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_e4991011-794b-45f3-8e69-0c0c11b243e7" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_aebfb437-0f2f-4bb0-91a9-ffb00454a114" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
  </link:definitionLink>
  <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:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_bafn_OperatingLeaseLiabilityContinuingOperations_109dcbdc-a6ea-444c-8cec-d9a1246e6ed1" xlink:href="bafn-20251231.xsd#bafn_OperatingLeaseLiabilityContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract" xlink:to="loc_bafn_OperatingLeaseLiabilityContinuingOperations_109dcbdc-a6ea-444c-8cec-d9a1246e6ed1" xlink:type="arc" order="31"/>
  </link:definitionLink>
</link:linkbase>
