| Kosai River | |
| Subdivision Type1: | Country |
| Subdivision Name1: | India |
| Subdivision Type2: | State |
| Subdivision Name2: | West Bengal |
| Subdivision Type5: | City |
| Subdivision Name5: | Kharagpur |
The Kosai River (Hindi: कोसै नदी) is a small river located near Kharagpur in the Indian state of West Bengal. It is the primary source of water supply for the township and the Indian Institute of Technology, Kharagpur.