The Ruvubu River (also spelled Rurubu and Ruvuvu) is a river in central Africa whose waters gather from the most distant, southern portion of the Nile basin. Its total length is 416 km (258 mi), with a drainage basin of 14,000 km2 (5,400 sq mi). It rises north of Burundi, near Kayanza, and then does a southward arc through Burundi, which is joined by the Ruvyironza River near Gitega. From there, it runs northeast, through the Ruvubu National Park, up to the Tanzanian border. After a stretch along the border, the Ruvubu properly crosses Tanzania before joining the Nyabarongo River on the Tanzania–Rwanda border near Rusumo Falls to form the Kagera River.
The Ruvubu gets its name from the Kirundi word for hippopotamus, imvubu because the river is home to many hippos.