Aust-Agder County Municipality (Norwegian: Aust-Agder fylkeskommune) was the regional governing administration of the old Aust-Agder county in Norway. The county municipality was established on 1 January 1976 when the law was changed to allow elected county councils in Norway. The county municipality was dissolved on 1 January 2020, when Aust-Agder was merged with the neighboring Vest-Agder county, creating the new Agder county which is led by the Agder County Municipality.