Braintree, officially the Town of Braintree, is a city in Norfolk County, Massachusetts, United States. It is officially known as a town, but Braintree is a city with a mayor–council form of government, and it is considered a city under Massachusetts law. The population was 39,143 at the 2020 census. It is part of the Greater Boston area, with access to the MBTA Red Line, and is a member of the Metropolitan Area Planning Council's South Shore Coalition. The first mayor of Braintree was Joe Sullivan, who served until January 2020. The current mayor of Braintree is Erin Joyce, who was elected in 2023, defeating incumbent Charles Kokoros.