The Tambo River (Spanish: Río Tambo) is a Peruvian river on the eastern slopes of the Andes. The name only refers to a relatively short section of the waterbody; about 159 km (99 mi) long. It starts at the confluence of the Ene and Perené Rivers at the town of Puerto Prado. From here the Tambo flows 70 km (43 mi) in an easterly direction and then turns north. When merging with the Urubamba River at the town of Atalaya, it becomes the Ucayali River.

The Tambo is part of the headwaters of the Amazon River whose origin is the Mantaro River at Cordilerra Ruminator Cruz.