<?xml version="1.0" encoding="US-ASCII" standalone="no"?>
    <!-- Field: Doc-Info; Name: Generator; Value: GoFiler Complete; Version: 6.5b -->
    <!-- Field: Doc-Info; Name: VendorURI; Value: https://www.novaworks.com -->
    <!-- Field: Doc-Info; Name: Status; Value: 0x00000000 -->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#HoldingsByIndustrySector" roleURI="http://xbrl.sec.gov/oef/role/HoldingsByIndustrySector" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#HoldingsByGeographicRegion" roleURI="http://xbrl.sec.gov/oef/role/HoldingsByGeographicRegion" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#HoldingsByCreditQuality" roleURI="http://xbrl.sec.gov/oef/role/HoldingsByCreditQuality" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#HoldingsByMaturity" roleURI="http://xbrl.sec.gov/oef/role/HoldingsByMaturity" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#HoldingsByAssetCategory" roleURI="http://xbrl.sec.gov/oef/role/HoldingsByAssetCategory" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#HoldingsByOtherCategory" roleURI="http://xbrl.sec.gov/oef/role/HoldingsByOtherCategory" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#HoldingsByOtherCategory2" roleURI="http://xbrl.sec.gov/oef/role/HoldingsByOtherCategory2" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#LargestHoldings" roleURI="http://xbrl.sec.gov/oef/role/LargestHoldings" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#ProspectusOnly" roleURI="http://xbrl.sec.gov/rr/role/ProspectusOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#RiskOnly" roleURI="http://xbrl.sec.gov/rr/role/RiskOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#CoregistrantOnly" roleURI="http://xbrl.sec.gov/oef/role/CoregistrantOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#SeriesOnly" roleURI="http://xbrl.sec.gov/oef/role/SeriesOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#ClassOnly" roleURI="http://xbrl.sec.gov/oef/role/ClassOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#PerformanceMeasureOnly" roleURI="http://xbrl.sec.gov/rr/role/PerformanceMeasureOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#HoldingAssetCategoryOnly" roleURI="http://xbrl.sec.gov/oef/role/HoldingAssetCategoryOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#BroadBasedIndexOnly" roleURI="http://xbrl.sec.gov/oef/role/BroadBasedIndexOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#AdditionalIndexOnly" roleURI="http://xbrl.sec.gov/oef/role/AdditionalIndexOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#IndustrySectorOnly" roleURI="http://xbrl.sec.gov/oef/role/IndustrySectorOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#GeographicRegionOnly" roleURI="http://xbrl.sec.gov/oef/role/GeographicRegionOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#CreditQualityOnly" roleURI="http://xbrl.sec.gov/oef/role/CreditQualityOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#MaturityOnly" roleURI="http://xbrl.sec.gov/oef/role/MaturityOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#Other1CategoryOnly" roleURI="http://xbrl.sec.gov/oef/role/Other1CategoryOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#Other2CategoryOnly" roleURI="http://xbrl.sec.gov/oef/role/Other2CategoryOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#LargestHoldingOnly" roleURI="http://xbrl.sec.gov/oef/role/LargestHoldingOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#SalesLoadOnly" roleURI="http://xbrl.sec.gov/oef/role/SalesLoadOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#HoldingMeasureOnly" roleURI="http://xbrl.sec.gov/oef/role/HoldingMeasureOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#ValueMeasureOnly" roleURI="http://xbrl.sec.gov/oef/role/ValueMeasureOnly" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll" arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/rr/role/ProspectusOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/rr/role/RiskOnly">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#oef_AllRisksMember" xlink:label="loc_oefAllRisksMember" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_ActiveManagementRiskMember" xlink:label="loc_rbbActiveManagementRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbActiveManagementRiskMember" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_AmericanDepositaryReceiptsADRsMember" xlink:label="loc_rbbAmericanDepositaryReceiptsADRsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbAmericanDepositaryReceiptsADRsMember" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_CyberSecurityRiskMember" xlink:label="loc_rbbCyberSecurityRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbCyberSecurityRiskMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_DividendPayingRiskMember" xlink:label="loc_rbbDividendPayingRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbDividendPayingRiskMember" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_EquitySecuritiesRiskMember" xlink:label="loc_rbbEquitySecuritiesRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbEquitySecuritiesRiskMember" xlink:type="arc" order="40" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_ETFInvestmentRiskMember" xlink:label="loc_rbbETFInvestmentRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbETFInvestmentRiskMember" xlink:type="arc" order="50" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_LargeCapCompaniesRiskMember" xlink:label="loc_rbbLargeCapCompaniesRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbLargeCapCompaniesRiskMember" xlink:type="arc" order="60" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_MidCapCompaniesRiskMember" xlink:label="loc_rbbMidCapCompaniesRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbMidCapCompaniesRiskMember" xlink:type="arc" order="70" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_MarketRiskMember" xlink:label="loc_rbbMarketRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbMarketRiskMember" xlink:type="arc" order="80" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_TaxRiskMember" xlink:label="loc_rbbTaxRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbTaxRiskMember" xlink:type="arc" order="90" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_ValueInvestingRiskMember" xlink:label="loc_rbbValueInvestingRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbValueInvestingRiskMember" xlink:type="arc" order="100" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_AmericanDepositaryReceiptsADRsAndGlobalDepositoryReceiptsGDRsRiskMember" xlink:label="loc_rbbAmericanDepositaryReceiptsADRsAndGlobalDepositoryReceiptsGDRsRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbAmericanDepositaryReceiptsADRsAndGlobalDepositoryReceiptsGDRsRiskMember" xlink:type="arc" order="110" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_EarlyCloseOrTradingHaltRiskMember" xlink:label="loc_rbbEarlyCloseOrTradingHaltRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbEarlyCloseOrTradingHaltRiskMember" xlink:type="arc" order="120" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_EmergingMarketsRiskMember" xlink:label="loc_rbbEmergingMarketsRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbEmergingMarketsRiskMember" xlink:type="arc" order="130" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_ForeignMarketsRiskMember" xlink:label="loc_rbbForeignMarketsRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbForeignMarketsRiskMember" xlink:type="arc" order="140" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_ForeignInvestmentRiskMember" xlink:label="loc_rbbForeignInvestmentRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbForeignInvestmentRiskMember" xlink:type="arc" order="150" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_NewFundRiskMember" xlink:label="loc_rbbNewFundRiskMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefAllRisksMember" xlink:to="loc_rbbNewFundRiskMember" xlink:type="arc" order="160" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/CoregistrantOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/SeriesOnly">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_S000106168Member" xlink:label="loc_rbbS000106168Member" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_rbbS000106168Member" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_S000106169Member" xlink:label="loc_rbbS000106169Member" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_rbbS000106169Member" xlink:type="arc" order="10" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/ClassOnly">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#oef_ShareClassDomain" xlink:label="loc_oefShareClassDomain" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_C000277001Member" xlink:label="loc_rbbC000277001Member" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefShareClassDomain" xlink:to="loc_rbbC000277001Member" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_C000277002Member" xlink:label="loc_rbbC000277002Member" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefShareClassDomain" xlink:to="loc_rbbC000277002Member" xlink:type="arc" order="10" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/rr/role/PerformanceMeasureOnly">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#oef_PerformanceMeasureDomain" xlink:label="loc_oefPerformanceMeasureDomain" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_SAndP500TotalReturnIndexMember" xlink:label="loc_rbbSAndP500TotalReturnIndexMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefPerformanceMeasureDomain" xlink:to="loc_rbbSAndP500TotalReturnIndexMember" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_MSCIACWIexUSAHighDividendYieldTotalReturnIndexMember" xlink:label="loc_rbbMSCIACWIexUSAHighDividendYieldTotalReturnIndexMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefPerformanceMeasureDomain" xlink:to="loc_rbbMSCIACWIexUSAHighDividendYieldTotalReturnIndexMember" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="rbb-20260704.xsd#rbb_SAndPFiveHundredTotalReturnIndexMember" xlink:label="loc_rbbSAndPFiveHundredTotalReturnIndexMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oefPerformanceMeasureDomain" xlink:to="loc_rbbSAndPFiveHundredTotalReturnIndexMember" xlink:type="arc" order="20" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/HoldingAssetCategoryOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/BroadBasedIndexOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/AdditionalIndexOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/IndustrySectorOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/GeographicRegionOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/CreditQualityOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/MaturityOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/Other1CategoryOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/Other2CategoryOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/LargestHoldingOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/SalesLoadOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/HoldingMeasureOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/ValueMeasureOnly" />
</link:linkbase>
