The Morkill River originates at Big Shale Hill in the Park Ranges of the Rocky Mountains near Interpass Ridge on the continental divide. It flows generally west through the mountains, collecting many tributaries including Cushing Creek, Forgetmenot Creek, and Hellroaring Creek. The Morkill turns southwest as it enters the Rocky Mountain Trench. It joins the Fraser River at Loos, in the Robson Valley portion of the Rocky Mountain Trench.