<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2018-10-24</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001676479</issuerCik>
        <issuerName>CapStar Financial Holdings, Inc.</issuerName>
        <issuerTradingSymbol>CSTR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001472966</rptOwnerCik>
            <rptOwnerName>Cunningham Jeffrey L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1201 DEMONBREUN STREET, SUITE 700</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NASHVILLE</rptOwnerCity>
            <rptOwnerState>TN</rptOwnerState>
            <rptOwnerZipCode>37203</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>49312</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17897</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Athens Employee Stock Ownership Plan</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>89559</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Athens 401(k) Plan</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Options (right to purchase)</value>
                <footnoteId id="F3"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.02</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2011-12-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2020-12-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>159080</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Pursuant to the Agreement and Plan of Merger, dated June 11, 2018 (the &quot;Merger Agreement&quot;),  by and between CapStar Financial Holdings, Inc. (&quot;CapStar&quot;) and Athens Bancshares Corporation (&quot;Athens&quot;), shares held in the Athens Employee Stock Option Plan (&quot;ESOP&quot;) were converted into the right to receive 2.864 shares of CapStar common stock. As of the date of this Form 3, the final number of ESOP shares allocable to the reporting person are not yet available.  Accordingly, set forth above is the estimate of the number of shares of CapStar common stock known to be beneficially owned by the reporting person at this time. The reporting person will report the final stock ownership numbers once they are determined. Additionally, although the ESOP has technically been terminated, the ESOP shares have not yet been transferred to a new account due to administrative processing of transfer documentation.</footnote>
        <footnote id="F2">Pursuant to the Merger Agreement, shares held in the Athens 401(k) Plan were also converted into the right to receive 2.864 shares of CapStar common stock. Although the Athens 401(k) has technically been terminated, as of the date of this Form 3, the 89,559 shares in the 401(k) Plan have not yet been transferred to a new account due to administrative processing of transfer documentation.</footnote>
        <footnote id="F3">These options vested in approximately five equal installments beginning on the first anniversary of the December 15, 2010 grant date.</footnote>
    </footnotes>

    <remarks>Exhibit 24 - Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Jeffrey L. Cunningham</signatureName>
        <signatureDate>2018-11-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
