Johnston is a town in Edgefield County, South Carolina, United States. The population was 2,336 at the 2000 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."
Johnston is located at 33°49′55″N 81°48′8″W / 33.83194°N 81.80222°W / 33.83194; -81.80222 (33.831927, -81.802304).
According to the United States Census Bureau, the town has a total area of 2.6 square miles (6.7 km²), of which, 2.5 square miles (6.5 km²) of it is land and 0.1 square miles (0.2 km²) of it (2.33%) is water.