2021 Western & Southern Open – Men's singles

Men's singles
2021 Western & Southern Open
Champion Alexander Zverev
Runner-up Andrey Rublev
Score6–2, 6–3
Draw56 (7 Q / 4 WC )
Seeds16

Alexander Zverev defeated Andrey Rublev in the final, 6–2, 6–3 to win the men's singles tennis title at the 2021 Cincinnati Masters. It was his fifth Masters 1000 title and 17th career singles title on the ATP Tour.

Novak Djokovic was the reigning champion, but did not participate.