Named for the first governor of Massachusetts, Winthrop was originally part of an area called Winnesimmet by Native Americans. The peninsula on which the town is located was annexed to Boston in 1630 and became a grazing area for farm animals.

In 1739, what is now Chelsea, Revere and Winthrop withdrew from Boston due to disputes, and became the Town of Chelsea. In 1846, Revere and Winthrop seceded from Chelsea to become North Chelsea. It wasn't until 1852 that Winthrop was incorporated as a town in its own right.