Suffolk County (/ˈsʌfək/ SUF-ək) is located in the Commonwealth of Massachusetts, in the United States.

[3] The traditional county seat is Boston, the state capital and the largest city in Massachusetts.

The county was created by the Massachusetts General Court on May 10, 1643, when it was ordered "that the whole plantation within this jurisdiction be divided into four shires".

Suffolk initially contained Boston, Roxbury, Dorchester, Dedham, Braintree, Weymouth, Hingham and Hull.

In 2012 Barack Obama received 77.4% of the vote, compared to 20.8% for former governor of Massachusetts Mitt Romney.

The Suffolk County Sheriff's Department's primary responsibility is oversight of the Nashua Street Jail and the South Bay House of Correction.

These were built in the 1990s to replace the historic Charles Street Jail and Deer Island Prison, respectively.

The Suffolk County Sheriff's Department was among those named in a 2020 WBUR report about the neglect of inmates with medical conditions in Massachusetts prisons leading to their deaths.