The Redstone River is a river in the municipality of Dysart et al, Haliburton County in central Ontario, Canada that flows from southern Algonquin Provincial Park to the Gull River.

The river begins at Upper Redstone Lake in southern Algonquin Provincial Park.

It flows southwest through the Haliburton Forest to Eyre Lake where it takes in the right tributary Eyre Creek, then through Little Redstone Lake to Redstone Lake where it takes in the left tributary Harburn Creek.

At the southeast, the East Redstone Dam controls the outflow to and is the source of the East Redstone River, which flows downstream over the East Redstone River Dam to Eagle lake on the Gull River.

Since the Gull River system flows to the summit of the waterway at Balsam Lake, its tributaries including Redstone River serve as an important water flow control reservoir.