The 1984 United States Senate election in Kentucky was held on November 5, 1984. Incumbent Democratic Senator Walter Dee Huddleston lost re-election to a third term to Mitch McConnell by less than 0.5%. This is the last time a Senator from Kentucky lost re-election.
Despite Ronald Reagan winning nationwide in a landslide in the concurrent presidential election (even carrying Kentucky by a 20% margin), this was the only Republican flip of the 1984 Senate elections, and Huddelston significantly outperformed Democratic nominee Walter Mondale's margin of defeat in the concurrent presidential race.
Huddleston was unopposed in the Democratic Party's primary. Governor John Y. Brown Jr. filed to run in March 1984, but withdrew for health reasons a few weeks later.
Huddleston led in polling up until 2 months to election day against McConnell by as much as 40 points. McConnell attacked Huddleston for missed votes to make paid speeches in Congress, using television advertisements of bloodhounds trying to track down the Democratic Senator. Huddleston's 94% voting record was largely ignored. McConnell hired Roger Ailes for his campaign, a move he later called "one of the smartest moves I've ever made." Kentucky was a Democratic-leaning state up until McConnell's victory in 1984, though Ronald Reagan also carried the state. McConnell would serve with Democrat Wendell Ford until 1999, and served with Republicans thereafter. He later would become Senate Majority Leader.