| Avessac | |
| Native Name: | (Gallo) |
| Commune Status: | Commune |
| Arrondissement: | Châteaubriant-Ancenis |
| Canton: | Pontchâteau |
| Insee: | 44007 |
| Postal Code: | 44460 |
| Mayor: | Hubert du Plessis[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Redon Agglomération |
| Coordinates: | 47.6542°N -1.9883°W |
| Elevation M: | 76 |
| Elevation Min M: | 0 |
| Elevation Max M: | 81 |
| Area Km2: | 76.49 |
Avessac (in French pronounced as /avɛsak/; Gallo: Aveczac or Aveça, Breton: Avezeg) is a commune in the Loire-Atlantique department in western France.