San Sebastiano Curone is a comune in the Province of Alessandria in the Italian region Piedmont, located about 110 kilometres southeast of Turin and about 40 kilometres southeast of Alessandria, at the confluence of the Curone and Museglia streams. San Sebastiano Curone borders the municipalities of Brignano-Frascata, Dernice, Gremiasco, and Montacuto.