Kuusjoki is a former municipality in the Southwest Finland region of Finland. It was consolidated with the town of Salo on January 1, 2009, and is now part of Salo rather than an independent municipality.
Before the consolidation, Kuusjoki bordered several other municipalities. Its neighbours were Halikko, Koski, Kiikala, Marttila, Pertteli, Salo and Somero.