Two-time defending champion John McEnroe defeated Björn Borg in a rematch of the previous year's final, 4–6, 6–2, 6–4, 6–3 to win the men's singles tennis title at the 1981 US Open.

It was Borg's fourth runner-up finish at the US Open, his career-best finish at the event.

The final would mark the last major appearance of eleven-time major champion Borg, due to his later retirement from the sport.

He left the venue before the trophy ceremony, emotionally distraught.

John McEnroe is the champion; others show the round in which they were eliminated.