2021 Belgrade Challenger – Men's singles
| Men's singles | |
|---|---|
| 2021 Belgrade Challenger | |
| Champion | Roberto Carballés Baena |
| Runner-up | Damir Džumhur |
| Score | 6–4, 7–5 |
This was the first of the three tournaments held in Belgrade for the 2021 tennis season. Belgrade also hosted a joint ATP/WTA tournament.
Roberto Carballés Baena won the title after defeating Damir Džumhur 6–4, 7–5 in the final.