| 2021 San Marino Open | |
|---|---|
| Date | 9–15 August |
| Edition | 28th |
| Location | City of San Marino, San Marino |
| Champions | |
| Singles | |
 Holger Rune | |
| Doubles | |
 Zdeněk Kolář /  Luis David Martínez | |
The 2021 San Marino Open was a professional tennis tournament played on clay courts. The 28th edition of the tournament, which was part of the 2021 ATP Challenger Tour, took place in City of San Marino, San Marino between 9 and 15 August 2021.