The Vaal River is the largest tributary of the Orange River in South Africa.

It rises in the Drakensberg mountains east of Johannesburg and forms the boundary between Transvaal and the Orange Free State before joining the Orange southwest of Kimberley. The name Vaal comes from Afrikaans, and means "pale", which alludes to the greyish colors of its waters, especially noticed during flood season when much silt is carried.