| Semur-en-Vallon | |
| Commune Status: | Commune |
| Arrondissement: | Mamers |
| Canton: | Saint-Calais |
| Insee: | 72333 |
| Postal Code: | 72390 |
| Mayor: | Yvan Bosnyak[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Vallées de la Braye et de l'Anille |
| Coordinates: | 48.0239°N 0.6544°W |
| Elevation Min M: | 104 |
| Elevation Max M: | 184 |
| Area Km2: | 15.13 |
| Demonym: | Semurois, Semuroise |
Semur-en-Vallon is a commune in the Sarthe department in the region of Pays de la Loire in north-western France.