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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2016-12-08</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001540159</issuerCik>
        <issuerName>Stellar Biotechnologies, Inc.</issuerName>
        <issuerTradingSymbol>SBOT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001663298</rptOwnerCik>
            <rptOwnerName>Olson Charles V</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O STELLAR BIOTECHNOLOGIES, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>332 EAST SCOTT STREET</rptOwnerStreet2>
            <rptOwnerCity>PORT HUENEME</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>93041</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Share Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>15.20</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2021-11-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1250</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The option was granted by the Issuer to the Reporting Person, in connection with the Reporting Person's service on the Issuer's Scientific Advisory Board, on November 12, 2014. The option is fully vested and immediately exercisable.</footnote>
    </footnotes>

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

    <ownerSignature>
        <signatureName>/s/ Kathi Niffenegger, as Attorney in Fact</signatureName>
        <signatureDate>2016-12-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
