The Rangitata River is one of the braided rivers that helped form the Canterbury Plains in southern New Zealand. It flows southeast for 120 kilometres from the Southern Alps, entering the Pacific Ocean 30 kilometres northeast of Timaru.

Towards its mouth, the river splits into two streams, forming a large delta island (Rangitata Island). This island is crossed by State Highway 1 and thus is the only island other than the North Island and South Island to be connected directly by New Zealand's main state highway.