The Forks River begins at Forks Lake in the northwest of the
Unorganized West Part of Timiskaming District at an elevation of and exits east to Lower Forks Lake. Portions of both lakes lie in the northeastern portion of the
Unorganized, North Part of
Sudbury District, meaning that the Forks River drainage basin is in three Ontario districts. It heads northeast, then north, flows over a small dam, and takes in the left tributary Little Forks Creek arriving from Little Forks Lake. The river turns northwest, then curves back northeast, flows into the city of
Timmins in Cochrane District, and reaches its mouth at St. Peter Bay at the southern tip of Night Hawk Lake at an elevation of . ==Tributaries==