| Rosny-sur-Seine | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Rosny-sur-Seine 78.svg |
| Arrondissement: | Mantes-la-Jolie |
| Canton: | Mantes-la-Jolie |
| Insee: | 78531 |
| Postal Code: | 78710 |
| Mayor: | Pierre-Yves Dumoulin[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CU Grand Paris Seine et Oise |
| Coordinates: | 49.0006°N 1.6325°W |
| Elevation M: | 30 |
| Elevation Min M: | 17 |
| Elevation Max M: | 144 |
| Area Km2: | 19.36 |
Rosny-sur-Seine (in French pronounced as /ʁoni syʁ sɛn/, literally Rosny on Seine) is a commune in the Yvelines department in the Île-de-France in north-central France.