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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-06-23</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001412067</issuerCik>
        <issuerName>Oncothyreon Inc.</issuerName>
        <issuerTradingSymbol>ONTY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001471149</rptOwnerCik>
            <rptOwnerName>Ayer Capital Management, LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>230 CALIFORNIA, SUITE 600</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94111</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-06-23</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>112050</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3014138</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-06-23</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>28900</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.74</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2985238</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">These securities are held by investment funds and a managed account, the investment advisor of which is Ayer Capital Management, LP (the &quot;Advisor&quot;). ACM Capital Partners, LLC (the &quot;ACM&quot;) is the General Partner of the Advisor, Ayer Capital Parnters, LLC is the General Partner (the &quot;GP&quot;) of the investment funds. Mr. Venkatesan is the managing member of ACM and the general partner of the GP.</footnote>
        <footnote id="F2">Each of the Advisor, ACM, the GP, Ayer Capital Partners, LLC and Mr. Venkatesan disclaims beneficial ownership of these securities except to the extent of its or his pecuniary interest thereof, and the filing of this report shall not be deemed an admission of beneficial ownership for purposes of Section 16 or for any other purpose.</footnote>
        <footnote id="F3">Distribution of common stock, with shares valued at $8.74 on June 23, 2011, by limited partnership to limited partners.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>On behalf of Ayer Capital Management, LP - Jay Venkatesan, Managing Member</signatureName>
        <signatureDate>2011-06-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>On behalf of ACM Capital Partners, LLC, Jay Venkatesan, Managing Member</signatureName>
        <signatureDate>2011-06-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Jay Venkatesan</signatureName>
        <signatureDate>2011-06-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>On behalf of Ayer Capital Partners, LLC, Jay Venkatesan, Managing Member</signatureName>
        <signatureDate>2011-06-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
