| Mornac-sur-Seudre | |
| Commune Status: | Commune |
| Arrondissement: | Rochefort |
| Canton: | La Tremblade |
| Insee: | 17247 |
| Postal Code: | 17113 |
| Mayor: | Emmanuel Cretin[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CA Royan Atlantique |
| Coordinates: | 45.7106°N -1.0272°W |
| Elevation M: | 5 |
| Elevation Min M: | 0 |
| Elevation Max M: | 13 |
| Area Km2: | 9.5 |
Mornac-sur-Seudre (in French pronounced as /mɔʁnak syʁ sødʁ/, literally Mornac on Seudre) is a commune in the Charente-Maritime department in southwestern France.