Fairhaven is an unincorporated community in eastern Israel Township, Preble County, Ohio, United States. It lies along State Route 177 at its intersection with Israel-Somers Road. Four Mile Creek, which feeds into Acton Lake in southern Preble County, runs on the western edge of Fairhaven. It is located 10½ miles (17 kilometers) southwest of Eaton, the county seat of Preble County. The community is part of the Dayton Metropolitan Statistical Area.