2021 Mutua Madrid Open – Men's singles
| Men's singles | |
|---|---|
| 2021 Mutua Madrid Open | |
| Champion | Alexander Zverev |
| Runner-up | Matteo Berrettini |
| Score | 6–7(8–10), 6–4, 6–3 |
| Draw | 56 (8 Q / 4 WC ) |
| Seeds | 16 |
Alexander Zverev defeated Matteo Berrettini in the final, 6–7(8–10), 6–4, 6–3 to win the men's singles tennis title at the 2021 Madrid Open. It was his fourth Masters 1000 title, his first since the 2018 Madrid Open, and his 15th career ATP Tour singles title overall.
Novak Djokovic was the reigning champion from when the tournament was last held in 2019, but did not participate.
Following the third-round eliminations of Daniil Medvedev and Stefanos Tsitsipas, respectively, a first-time Masters 1000 singles finalist from the bottom half of the draw was guaranteed; Berrettini went on to become that player.