| Fonsomme | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Fonsomme (Aisne).svg |
| Arrondissement: | Saint-Quentin |
| Canton: | Saint-Quentin-2 |
| Insee: | 02319 |
| Postal Code: | 02110 |
| Mayor: | Colette Noël[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CA Saint-Quentinois |
| Coordinates: | 49.9031°N 3.4003°W |
| Elevation M: | 85 |
| Elevation Min M: | 82 |
| Elevation Max M: | 131 |
| Area Km2: | 9.6 |
Fonsomme (pronounced as /fr/; before 2011: Fonsommes)[2] is a commune in the Aisne department in Hauts-de-France in northern France.
The source of the river Somme lies in the commune.