The Oldzho (Russian: Ольджо; Yakut: Олдьо, Olco), also known as Oldyo (Ольдё) or Olduo (Олдьуо), is a river in the Verkhoyansk District, Sakha Republic, Russia.

[3] River Oldzho originates in a lake in the northeast of the Khadaranya Range, located in a valley formed by the northeastern slopes of the Khadaranya and the southern end of the Burkat Range.

The river flows first northwestwards, then makes a wide bend at the northern end of the Khadaranya Range and flows roughly southwestwards.

After passing the northwestern end of the Ymiysky Range its course forms meanders and the Oldzo is joined on its left side by the Nenneli (Неннели), its largest tributary.

[2] Finally it reaches the right bank of the Yana 587 km (365 mi) from its mouth and about 30 km (19 mi) downstream from the confluence of the Adycha.