| Lainville-en-Vexin | |
| Commune Status: | Commune |
| Arrondissement: | Mantes-la-Jolie |
| Canton: | Limay |
| Insee: | 78329 |
| Postal Code: | 78440 |
| Mayor: | Martine Quignard[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CU Grand Paris Seine et Oise |
| Coordinates: | 49.0603°N 1.8175°W |
| Elevation M: | 153 |
| Elevation Min M: | 93 |
| Elevation Max M: | 201 |
| Area Km2: | 7.67 |
Lainville-en-Vexin (in French pronounced as /lɛ̃vil ɑ̃ vɛksɛ̃/, literally Lainville in Vexin) is a commune in the Yvelines department in the Île-de-France region in north-central France.