Below is a chronological listing of the United States senators from Massachusetts. According to the Seventeenth Amendment to the United States Constitution adopted in 1913, U.S. senators are popularly elected for a six-year term. Elections are held the first Tuesday after November 1, and terms begin on January 3, about two months after the vote. Before 1914, and the enforcement of the Seventeenth Amendment, the state's U.S. senators were chosen by the Massachusetts General Court, and before 1935, their terms began March 4.

The current senators are Democrats Elizabeth Warren and Ed Markey. Ted Kennedy was Massachusetts's longest-serving senator, serving from 1962 until his death in 2009. Massachusetts is one of fifteen states alongside Arizona, Colorado, Florida, Georgia, Hawaii, Idaho, Indiana, Louisiana, Maine, Minnesota, Missouri, Nevada, South Dakota and Utah to have a younger senior senator and an older junior senator.

Through the 20th century, mid-term vacancies were filled with the governor's appointee, with the appointment expiring at the next biennial state election. In 2004, the Democratic-controlled state legislature changed the vacancy-filling process, mandating that a special election occur, which removed the governor's appointment power. This statute was enacted over the veto by the governor, Mitt Romney. The leadership of the Massachusetts legislature at the time was concerned that the Republican Governor Mitt Romney would appoint a Republican if Democratic Senator John Kerry were elected president of the United States in the 2004 election.^[1][2][3][4] Generally, the law requires a special election within 145 to 160 days from the date of the filing of a Senate resignation. The law contemplates resignations that become effective some period of time after the filing of the resignation, so long as the election occurs after effective date of the resignation.^[5]

While terminally ill with brain cancer, Ted Kennedy requested that the Massachusetts legislature change the law to allow an interim appointment. Kennedy died shortly thereafter, and the legislature quickly passed a bill providing for an interim appointment.^[6] On September 24, 2009, Governor Deval Patrick signed the bill, and appointed Paul G. Kirk, who had previously served as one of Kennedy's congressional aides and as chairman of the Democratic National Committee.

• List of United States representatives from Massachusetts
• United States congressional delegations from Massachusetts
• Elections in Massachusetts