The river rises east of the town of Redmond and then flows for approximately 27 kilometres and along with the Kalgan River drains into Oyster Harbour and finally King George Sound north east of Albany.
The river was named after an early explorer of the Australian and Patagonian coasts, Phillip Parker King, by Thomas Braidwood Wilson while exploring the region in December 1829. The estuarine zone of the river is from the mouth to 7 kilometres upstream to where Mill Brook joins the river.
The land along the river is estimated as being 83% cleared yet the water quality is generally healthy fresh water.
The main tributary of the King River is Mill Brook which joins the King about 2 kilometres north-west of the Upper King Bridge