Boylston is a town in Worcester County, Massachusetts, United States. The population was 4,355 at the 2010 census.
According to the United States Census Bureau, the town has a total area of 19.7 square miles (51 km2), of which 16.0 square miles (41 km2) is land and 3.6 square miles (9.3 km2), or 18.50%, is water. With a population of nearly 4400 residents, the town is predominantly a residential community. The Wachusett Reservoir, part of the water supply system managed by the Massachusetts Water Resources Authority for Greater Boston area, lies in the northwestern part of the town and covers about 5,000 acres (20 km2) of land. The town maintains approximately 45 miles (72 km) of roadway, has 9 miles (14 km) of sidewalks, and has its own Municipal Light Department, Water District, and volunteer fire and ambulance service. The town of Boylston is bordered by the towns of Shrewsbury, West Boylston, Sterling, Clinton, Berlin, and Northborough.
As of the 2000 census, there were 4,008 people, 1,573 households, and 1,140 families residing in the town. The population density was 250.0 inhabitants per square mile (96.5 /km2). There were 1,606 housing units at an average density of 100.2 per square mile (38.7 /km2).