Stefan Edberg defeated Jim Courier in the final, 6–2, 6–4, 6–0 to win the men's singles tennis title at the 1991 US Open. It was his first US Open singles title and fifth major singles title overall.
Pete Sampras was the defending champion, but lost in the quarterfinals to Courier.
Five-time champion Jimmy Connors, who turned 39 during the tournament, entered as a wildcard and impressively reached the semifinals before losing to Courier. Connors became the oldest male semifinalist at the tournament since Ken Rosewall in 1974.