| Chasné-sur-Illet | |
| Native Name: | (Gallo) |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Chasné-sur-Illet (Ille-et-Vilaine).svg |
| Coordinates: | 48.2422°N -1.5603°W |
| Insee: | 35067 |
| Postal Code: | 35250 |
| Arrondissement: | Rennes |
| Canton: | Liffré |
| Mayor: | Benoît Michot[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Liffré-Cormier Communauté |
| Elevation Min M: | 39 |
| Elevation Max M: | 81 |
| Area Km2: | 9.47 |
Chasné-sur-Illet (pronounced as /fr/; Gallo: Chasnaé,) is a commune in the Ille-et-Vilaine department in Brittany in northwestern France.
Inhabitants of Chasné-sur-Illet are called Chasnéens in French.