| Grand Morin | |
| Pushpin Map: | France#France Île-de-France |
| Mouth Location: | Marne |
| Mouth Coordinates: | 48.9003°N 2.8306°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | France |
| Length: | 118km (73miles) |
| Basin Size: | 1180km2 |
The Grand Morin (in French pronounced as /ɡʁɑ̃ mɔʁɛ̃/, literally Great Morin) is a 118km (73miles) long river in France, left tributary of the Marne. Its source is near the village of Lachy. Its course crosses the departments of Marne and Seine-et-Marne. It flows westwards through the towns of Esternay, La Ferté-Gaucher, Coulommiers and Crécy-la-Chapelle, finally flowing into the Marne in Esbly.
Its main tributary is the Aubetin.