The 2020 United States Senate election in Massachusetts was held on November 3, 2020, to elect a member of the United States Senate to represent the Commonwealth of Massachusetts, concurrently with the 2020 U.S. presidential election, as well as elections to the United States Senate in other states, elections to the United States House of Representatives, and various state and local elections. On September 1, incumbent senator Ed Markey defeated U.S. Representative Joe Kennedy III in a competitive primary for the Democratic nomination, and Kevin O'Connor defeated Shiva Ayyadurai for the Republican nomination. Markey went on to win the general election with 66.2% of the vote, and was thus re-elected to a second full term in a landslide.

Edward John Markey is an American lawyer, politician, and former Army reservist serving as the junior United States senator from Massachusetts since 2013. A member of the Democratic Party, he served 20 terms as the U.S. representative for Massachusetts's 7th congressional district from 1976 to 2013. Before his congressional career, he was a member of the Massachusetts House of Representatives from 1973 to 1976.