Ashburnham is a town in Worcester County, Massachusetts, United States. At the 2010 census, the town population was 6,081. It is home to Cushing Academy, a private preparatory boarding school.
Ashburnham contains the census-designated place of South Ashburnham.
Ashburnham was first settled by Europeans in 1736, and was officially incorporated in 1765. The name is of British origin, possibly drawn from the Earl of Ashburnham, in Pembrey, or the Sussex community of Ashburnham.
Ashburnham was originally made up of the lands granted to officers and soldiers of a 1690 expedition to Canada. It was called the Plantation of Dorchester-Canada until it was incorporated.
According to the United States Census Bureau, the town has a total area of 41.0 square miles (106 km2), of which 38.7 square miles (100 km2) is land and 2.3 square miles (6.0 km2) (5.68%) is water. Ashburnham has two distinct topographical areas, hilly to the east and relatively flat high ground to the west.