The Warren River is a medium sized river that rises 30 kilometres south-east of Manjimup at the confluence of the Tone and Perup Rivers. From that point it flows 137 kilometres in a south-westerly direction through the Warren State Forest and the D’Entrecasteaux National Park before discharging into the Southern Ocean. It has numerous tributaries including the Lefroy Brook that flows through the Pemberton caravan park.

The Warren River was named by James Stirling in 1831 after one of the admirals under whom he served while in action in North America, Admiral Sir John Borlase Warren.