Charlton is a town in Worcester County, Massachusetts, United States. The population was 12,981 at the 2010 census.According to the United States Census Bureau, the town has a total area of 43.8 square miles (113 km2), of which 42.5 square miles (110 km2) is land and 1.2 square miles (3.1 km2) (2.86%) is water.
Charlton was first settled in 1735. It was established as a District separated off from Oxford on January 10, 1755, and became a Town in 1775 by a law that made all Districts into Towns. It was named after Sir Francis Charlton. During the 1800s, farming continued to be the major occupation, but woolen mills were being built along some of the town's brooks by the turn of the twentieth century.