Swansea is a town in Bristol County in southeastern Massachusetts. It is located at the mouth of the Taunton River, just west of Fall River, 47 miles (76 km) south of Boston, and 12 miles (19 km) southeast of Providence, Rhode Island. The population was 17,144 at the 2020 census.

The villages of Hortonville, Barneyville and Ocean Grove are located in the town.

The town has a total area of 25.5 square miles (66 km²), of which 23.1 square miles (60 km²) is land and 2.5 square miles (6.5 km²), or 9.67%, is water. The town is bordered by Dighton on the northeast, Somerset on the east, Mount Hope Bay on the south, Warren, Rhode Island, on the southwest, Barrington, Rhode Island, on the west, and Seekonk and Rehoboth to the north. Part of the town's border with Somerset is made up of the Lees River. The Cole, Kickamuit and Palmer rivers also pass through the town on their way south to Mount Hope Bay (for the Kickamuit, Cole and Lees rivers) and Narragansett Bay (for the Palmer). The entire town is a part of the Narragansett Bay watershed area. The town's neighborhoods include Barneyville, North Swansea, Swansea Village, Birch Swamp Corner, Hortonville, Luther Corner, South Swansea, Touissett, Ocean Grove, and Smokerise. Swansea is 12 miles (19 km) southeast of Providence and 47 miles (76 km) south of Boston.