| Saint-Cyr-sous-Dourdan | |
| Commune Status: | Commune |
| Coordinates: | 48.569°N 2.0347°W |
| Insee: | 91546 |
| Postal Code: | 91410 |
| Arrondissement: | Étampes |
| Canton: | Dourdan |
| Mayor: | Jean-Pierre Moulin[1] |
| Term: | 2020 - 2026 |
| Elevation Min M: | 72 |
| Elevation Max M: | 160 |
| Area Km2: | 9.89 |
Saint-Cyr-sous-Dourdan (pronounced as /fr/, literally Saint-Cyr under Dourdan) is a commune in the Essonne department in Île-de-France in northern France.
Inhabitants of Saint-Cyr-sous-Dourdan are known as Saint-Cyriens.