| Flassigny | |
| Commune Status: | Commune |
| Arrondissement: | Verdun |
| Canton: | Montmédy |
| Insee: | 55188 |
| Postal Code: | 55600 |
| Mayor: | Pierre Guillaume[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Pays de Montmédy |
| Coordinates: | 49.4742°N 5.4417°W |
| Elevation M: | 252 |
| Elevation Min M: | 193 |
| Elevation Max M: | 337 |
| Area Km2: | 6.66 |
Flassigny (pronounced as /fr/) is a commune in the Meuse department in Grand Est in north-eastern France.
The river Othain forms all of the commune's eastern border; a Roman road forms most of its southern border.