| Mwiruzi River | |
| Pushpin Map: | Burundi |
| Subdivision Type1: | Country |
| Subdivision Name1: | Burundi |
| Subdivision Type2: | Province |
| Subdivision Name2: | Bubanza Province |
| Mouth: | Malagarasi River |
| Mouth Location: | Tanzanian border |
| Mouth Coordinates: | -2.9799°N 30.8496°W |
The Mwiruzi River (fr|link=no|Rivière Mwiruzi) is a river in northeastern Burundi, a tributary of the Malagarasi River.
The Mwiruzi River is in the Malagarasi River watershed.In Burundi, the Mwiruzi River flows through the Commune of Mishiha in the northeast of Cankuzo Province, marking the northeast border between Burundi and Tanzania.Its source is the quartzitic ridge of Gitwenge, where its tributaries the Mungwa and the Gahumo also take their source.The Gahumo flows along the northern border between Cankuzo and Tanzania to join the Mwiruzi.
A report prepared in 2000 for the FAO recommended resettling displaced persons in the Mwiruzi marshes in the province of Cankuzo.The demographic pressure in this area was low, and the marsh was mineral, so there should be no major problem in development.
The marshes in the watershed of the Mwiruzi River cover, of which or 41% were cultivated in 2014.As of 2014 the Nyanzari-Mwiruzi marsh and the Mwiruzi marsh, both in the Mishiha commune, were both managed.A Mwiruzi marsh was not managed.