| Ndji River | |
| Pushpin Map: | Central African Republic |
| Subdivision Type1: | Country |
| Subdivision Name1: | Central African Republic |
| Subdivision Type2: | Prefecture |
| Subdivision Name2: | Haute-Kotto |
| Mouth: | Kotto River |
| Mouth Location: | Bria |
The Ndji River, or Ndgii River, Dji River, Kpéo River, is a river of the Central African Republic. It is a left tributary of the Kotto River.
The Ndji river is long.It rises to the east of the Pata sandstone plateau and skirts the eastern escarpment before crossing it.Its source at 7.3333°N 21.5167°W is at an elevation of .It drops by to its mouth on the Kotto at 6.8°N 22.2667°W at an elevation of .
The Belgian explorer Léon Hanolet travelled up the valley of the Bali (Mbali) river and the upper Kotto River in 1894, following the road of the Arab caravans.His expedition reached Dabago at 6.9667°N 23.1667°W on the Ndji River.He described the country as flat, and sometimes walked for six hours without crossing a stream.
The river is home to the Syncerus caffer aequinoctialis subspecies of the African buffalo.