| Mesnil-Martinsart | |
| Commune Status: | Commune |
| Arrondissement: | Péronne |
| Canton: | Albert |
| Insee: | 80540 |
| Postal Code: | 80300 |
| Mayor: | Roger Roussel[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Pays du Coquelicot |
| Coordinates: | 50.0544°N 2.6492°W |
| Elevation M: | 128 |
| Elevation Min M: | 62 |
| Elevation Max M: | 144 |
| Area Km2: | 8.76 |
Mesnil-Martinsart (in French pronounced as /menil maʁtɛ̃saʁ/) is a commune in the Somme département in Hauts-de-France in northern France.
The commune is situated on the D174 road, some 22miles northeast of Amiens.