Blackville is located in northeastern Barnwell County at 33°21′25″N 81°16′22″W﻿ / ﻿33.35694°N 81.27278°W﻿ / 33.35694; -81.27278 (33.357078, -81.272649). U.S. Route 78 passes through the town, leading west 31 miles (50 km) to Aiken and east 15 miles (24 km) to Bamberg.