The 1984 United States Senate election in Montana took place on November 6, 1984. Incumbent United States Senator Max Baucus, who was first elected in 1978, ran for re-election. He easily won renomination in the Democratic primary, and advanced to the general election, where he faced Chuck Cozzens, a former State Representative and the Republican nominee. Despite President Ronald Reagan's strong performance in the state that year, Baucus was able to easily win a second term over Cozzens.
Baucus won both congressional districts, including one that elected a Republican.