| Seyssel | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Seyssel (Haute-Savoie).svg |
| Arrondissement: | Saint-Julien-en-Genevois |
| Canton: | Saint-Julien-en-Genevois |
| Insee: | 74269 |
| Postal Code: | 74910 |
| Mayor: | Gérard Lambert[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CC Usses et Rhône |
| Coordinates: | 45.9597°N 5.8372°W |
| Elevation M: | 265 |
| Elevation Min M: | 250 |
| Elevation Max M: | 937 |
| Area Km2: | 16.86 |
Seyssel (pronounced as /fr/; frp|Sèssél) is a commune in the Haute-Savoie department in the Auvergne-Rhône-Alpes region in south-eastern France.
The part of the town across the Rhône is also named Seyssel but located on the western bank of the Rhône in the Ain department. It is a rare case in France of two homonymous communes adjacent to each other, similar to the situation of the village of Saint-Santin, divided between the communes of Saint-Santin (Aveyron) and Saint-Santin-de-Maurs (Cantal).
The Fier forms most of the commune's southern border, then flows into the Rhône, which forms the commune's western border.