John McEnroe defeated Ivan Lendl in the final, 6–3, 6–4, 6–1 to win the men's singles tennis title at the 1984 US Open.

It was his fourth US Open singles title and seventh and last major singles title overall.

It was Lendl's third consecutive runner-up finish at the US Open.

Jimmy Connors was the two-time defending champion, but was defeated by McEnroe in the semifinals, in the last match between the pair at a major singles tournament.