The Tambo River (Spanish: Río Tambo) is a Peruvian river on the eastern slopes of the South American Andes.
The Tambo is part of the headwaters of the Amazon River whose origin is the Apúrimac River at Nevado Mismi and which becomes Ene River before its waters form the Tambo River. The Tambo River is formed at at the confluence of the Perené River and the Ene River, at the town of Puerto Prado, 400 m above sea level. The river flows 70 km in an easterly direction southeast of Gran Pajonal and then turns north, its total length being 159 km.
At , the Tambo River joins the Urubamba River, at the town of Atalaya, 287 m above sea level, and is called the Ucayali River from then on.