The Dillon River of the Marlborough Region of New Zealand rises in the Inland Kaikōura Range near Carters Saddle.

From its source, it flows south-west for 28 kilometres (17 mi) to join with the upper Waiau Toa / Clarence River 20 kilometres (12 mi) northeast of Hanmer Springs.

The river's course lies largely parallel with that of the Acheron River, which flows 8 kilometres (5 mi) to the west.

[1] The river was named after the 19th-century settler Constantine Dillon, who owned a sheep run near the Omaka River.

This article about a river in the Marlborough Region is a stub.