The river rises below the Caroline Range near Mount Lacy and then flows south to the west of Mount Elizabeth then through the Barnett River gorge crossing the Gibb River Road near the Mount Barnett roadhouse before flowing into the Hann River in the Philip Range near Mount Caroline.
It was named by the first European to explore the river, Frank Hann, who had seen it during his expedition to the region in 1898. He named the river after Alfred Barnett, who was the manager of Balmaningarra Station, which is situated along the Lennard River.[3]