South Mount Vernon is a census-designated place (CDP) in Knox County, Ohio, United States, adjacent to the city of Mount Vernon.

[2] The CDP is west of the center of Knox County, in Clinton Township.

It is bordered to the north, east, and south by the city of Mount Vernon.

U.S. Route 36 (Harcourt Road) runs through the west side of the community, leading north and east into Mount Vernon, and southwest 22 miles (35 km) to Sunbury.

This Knox County, Ohio state location article is a stub.