2021 Serbia Open – Men's singles
| Men's singles | |
|---|---|
| 2021 Serbia Open | |
| Champion | Matteo Berrettini |
| Runner-up | Aslan Karatsev |
| Score | 6–1, 3–6, 7–6(7–0) |
| Draw | 28 (4 Q/ 3 WC) |
| Seeds | 8 |
Matteo Berrettini defeated Aslan Karatsev in the final, 6–1, 3–6, 7–6(7–0) to win the men's singles tennis title at the 2021 Serbia Open.
Andreas Seppi was the reigning champion from when the event was last held in 2012, but he decided not to participate this year.