Watertown is an unincorporated community in southwestern Watertown Township, Washington County, Ohio, United States. Although it is unincorporated, it has a post office, with the ZIP code of 45787. It lies near the intersection of State Routes 339 and 676 near Wolf Creek, which meets the Muskingum River at Waterford to the north.
In 1986, the community was listed on the National Register of Historic Places in 1986 as a historic district, the "Watertown Historic District." Seventy-five buildings compose the district: three are built of brick, and the rest are white weatherboarded structures. Most of the contributing properties were built after the Civil War and before World War I. The importance of the district is derived from the architecture of most of its houses, largely because local carpenters made extensive use of Stick-Eastlake ornamental elements in their designs.