Castlewood is a census-designated place (CDP) in Russell County, Virginia, United States. The population was 2,036 at the 2000 census. Castlewood was an incorporated town from 1991 to 1997, when it reverted to unincorporated status.
Castlewood is located at 36°52′43″N 82°17′21″W / 36.87861°N 82.28917°W / 36.87861; -82.28917 (36.878614, -82.289229).
According to the United States Census Bureau, the CDP has a total area of 7.2 square miles (18.7 km²), of which, 7.2 square miles (18.6 km²) of it is land and 0.14% is water.