jats:titleAjats:scbstract</jats:sc> </jats:title> jats:pA set of infinitesimal Virasoro jats:subL</jats:sub> ⊗ Virasoro jats:subR</jats:sub> diffeomorphisms are presented which act non-trivially on the horizon of a generic Kerr black hole with spin J. The covariant phase space formalism provides a formula for the Virasoro charges as surface integrals on the horizon. Integrability and associativity of the charge algebra are shown to require the inclusion of ‘Wald-Zoupas’ counterterms. A counterterm satisfying the known consistency requirement is constructed and yields central charges jats:italicc</jats:italic> jats:sub jats:italicL</jats:italic> </jats:sub> = jats:italicc</jats:italic> jats:sub jats:italicR</jats:italic> </jats:sub> = 12jats:italicJ</jats:italic>. Assuming the existence of a quantum Hilbert space on which these charges generate the symmetries, as well as the applicability of the Cardy formula, the central charges reproduce the macroscopic area-entropy law for generic Kerr black holes.</jats:p>