Islandton is an unincorporated community and census-designated place in Colleton County, South Carolina, United States. As of the 2010 census, its population was 70. South Carolina Highway 63 passes through the community, leading east 17 miles (27 km) to Walterboro, the county seat, and southwest 10 miles (16 km) to Varnville. Islandton has a post office with ZIP code 29929.