The Gascoyne River is a river in the Gascoyne region of Western Australia. At 865 kilometres, it is the longest river in Western Australia.
The Gascoyne River comprises three branches in its upper reaches. Draining the Collier Range, the river rises as the Gascoyne River (North Branch) on Three Rivers Station near the Great Northern Highway, 100 kilometres northeast of Peak Hill and flows for approximately 125 kilometres. The Gascoyne River (Middle Branch) rises west of Beyondie Lakes, east of Kumarina and east of the Great Northern Highway and flows for approximately 15 kilometres. The Gascoyne River (South Branch) rises near the Doolgunna homestead and flows for approximately 15 kilometres.
