Attleboro is a city in Bristol County, Massachusetts, United States. It was once known as "The Jewelry Capital of the World" for its many jewelry manufacturers. According to the 2020 census, Attleboro had a population of 46,461.

Attleboro has an area of 27.772 square miles , of which 26.779 square miles is land and 0.994 square miles , or 3.59%, is water. Its borders form an irregular polygon that resembles a truncated triangle pointing west. It is bordered by North Attleborough to the north, Mansfield and Norton to the east, Rehoboth, Seekonk, and Pawtucket, Rhode Island, to the south, and Cumberland, Rhode Island, to the west, as well as sharing a short border with Central Falls, Rhode Island through the Blackstone River. It includes the areas known as City Center, Briggs Corner, West Attleboro, East Corner, East Attleboro, North Corner, Maple Square, Camp Hebron, Oak Hill, Dodgeville, East Junction, Hebronville, Park Square, and South Attleboro.