| Mucajaí River | |
| Pushpin Map: | Brazil |
| River System: | Branco River |
| Mouth Coordinates: | 2.4325°N -60.8431°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | Brazil |
The Mucajaí River is a river of Roraima state in northern Brazil. It is a right tributary of the Branco River.
Part of the river's basin is in the Roraima National Forest.