Johnston is a town in Edgefield County, South Carolina, United States. The population was 2,362 at the 2010 census. It is part of the Augusta, Georgia, metropolitan area. The town's official welcome sign states that it is "Peach Capital of the World".

Edgefield County is a county located on the western border of the U.S. state of South Carolina. As of the 2020 census, its population was 25,657. Its county seat and largest community is Edgefield. The county was established on March 12, 1785.