Woonsocket is a city in Sanborn County, South Dakota, United States. The population was 655 at the 2010 census. It is the county seat of Sanborn County. Woonsocket is named after Woonsocket, Rhode Island.
Woonsocket is located at 44°03′10″N 98°16′25″W / 44.052797°N 98.273699°W / 44.052797; -98.273699.
According to the United States Census Bureau, the city has a total area of 0.8 square miles (2.0 km2), of which, 0.8 square miles (2.0 km2) of it is land and 1.27% is water.