Haydenville is a census-designated place in southern Green Township, Hocking County, Ohio, United States. It lies along U.S. Route 33 and the Hocking River, southeast of the city of Logan, the county seat of Hocking County. Its elevation is 705 feet (215 m), and it is located at (39°28′55″N82°19′42″W) (39.4820130, -82.3282074). Although Haydenville is unincorporated, it has a post office, established on January 10, 1870, and a nearby cemetery.