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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-02-19</periodOfReport>

    <issuer>
        <issuerCik>0001436425</issuerCik>
        <issuerName>HOME BANCORP, INC.</issuerName>
        <issuerTradingSymbol>HBCP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001676827</rptOwnerCik>
            <rptOwnerName>RADER CHRIS P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O HOME BANCORP, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>503 KALISTE SALOOM ROAD</rptOwnerStreet2>
            <rptOwnerCity>LAFAYETTE</rptOwnerCity>
            <rptOwnerState>LA</rptOwnerState>
            <rptOwnerZipCode>70508</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-02-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>59.50</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17713.7563</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8826.325</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By IRA</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes the grant of 550 restricted stock units pursuant to the Issuer's 2014 Incentive Plan that vest in equal installments at the rate of 20% per year commencing on May 12, 2022 and that may be settled only in shares of the Issuer's common stock.</footnote>
        <footnote id="F2">Includes the grant of 600 restricted stock units pursuant to the Issuer's 2021 Incentive Plan that vest in equal installments at the rate of 20% per year commencing on May 12, 2023 and that may be settled only in shares of the Issuer's common stock.</footnote>
        <footnote id="F3">Includes the grant of 600 restricted stock units pursuant to the Issuer's 2021 Incentive Plan that vest in equal installments at the rate of 20% per year commencing on May 12, 2024 and that may be settled only in shares of the Issuer's common stock.</footnote>
        <footnote id="F4">Includes the grant of 600 restricted stock units pursuant to the Issuer's 2021 Incentive Plan that vest in equal installments at the rate of 20% per year commencing on May 12, 2025 and that may be settled only in shares of the Issuer's common stock.</footnote>
        <footnote id="F5">Includes the grant of 700 restricted stock units pursuant to the Issuer's 2021 Incentive Plan that vest in equal installments at the rate of 20% per year commencing on May 12, 2026 and that may be settled only in shares of the Issuer's common stock.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Chris P. Rader</signatureName>
        <signatureDate>2026-02-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
