List of Ontario rivers

List of rivers arranged by watershed

Hudson Bay Watershed
- Black Duck River
- Severn River
  - Beaver River
  - Fawn River
  - Nagagamisis River, Nagagamisis Lake
  - Obakamiga River
  - Pike Alley
  - Sachigo River
  - Usiske River
- Winisk River
  - Pipestone River
- Albany River
  - Kenogami River
    - Pagwachuan River
    - Flint River, Flint Lake
      - Holles Creek
    - Burrows River, Burrows Lake
      - Murky Creek
      - [[]], Cotoneaster Lake
    - Kemogamisis River,
      - Isis Creek
      - [[]], [[]]
    - Fecteau Lake
    - Wintering Lake
      - Westside Bay
      - Pout River
  - Drowning River
- Berens River
- Bloodvein River
- Winnipeg River
  - Lake of the Woods Watershed
    - Rainy River
    - Rainy Lake
      - Turtle River
      - Pipestone River
    - Seine River
      - Farrington Creek
      - Cherry River
      - Manitou River
        Manitou Stretch, Lower and Upper Manitou Lake
        Peep Bay
        Grant Lake
        Mosher Bay
      - McTaggart Creek
      - MacDonald's Inlet
      - Big Canoe River, Cuttle Lake
      - Clement Creek
      - Sleeman Creek
  - English River
    - Vermilion River
    - Wabigoon River
    - Wapesi River
- James Bay Watershed
  - Moose River
    - Kwataboahegan River
    - Cheepash River
    - Abitibi River
      - Frederick House River
    - Mattagami River
      - Kapuskasing River
        [[]]
        [[]], Brunswick Lake
        Doherty Creek
        
        Fire River
        
        Kabinakagami River
        Brulé Creek
        
        Edison Creek
        Woolrich Creek
        Bear Creek
        Nameigos River
        Five Mile Creek
        
        Torrance Creek
        Hopkins Creek
        Remi River, Remi Lake
      - Forks River
        Chapleau River
      - Groundhog River
    - Missinaibi River
      - Mattawitchewan River
        Albany Forks
        Cameron Creek
        Oba River, Oba Lake
      - Pivabiska River
      - Opasatika River
      - Soweska River
  - Kesagami River
  - Kattawagami River
Atlantic Ocean Watershed
- Lake Erie Watershed
  - Detroit River
  - Lynn River
  - Grand River
    - Conestoga River
      - Speed River
  - Lake St. Clair Watershed
    - Little River
    - Puce River
    - Belle River
    - Ruscon River
    - Thames River
      - Dingman Creek
      - Jeanettes Creek
      - McGregor Creek
      - Medway Creek
      - Pottersburg Creek
      - Stoney Creek
      - Waubuno Creek
    - Sydenham River
    - St. Clair River
- Lake Huron, Georgian Bay, Watershed (in alphabetical order)
  - Ausable River
  - Bayfield River
  - Beaver River
    - Boyne River
  - Bighead River
  - Blind River
  - French River
    - Wanapitei River
    - Pillow River
    - Murdock River
    - Wolseley River
    - Little French River
    - Restoule River
    - Hall River
    - Lake Nipissing Watershed
      - Amateewakea River
      - Cache River
      - Sturgeon River
        Smoky River
      - Little Sturgeon River
      - Duchesnay River
      - La Vase River
      - Wasi River
      - South River
  - Kagawong River
  - Magnetawan River
  - Maitland River
  - Manitou River
  - Mindemoya River
  - Mississagi River
  - Moon River (Cottage Country)
    - Muskoka River
      - Indian River
      - Hollow River
      - Oxtongue River
      - Buck River
      - East River
  - Musquash River
  - Nottawasaga River
    - Boyne River
    - Mad River
    - Pine River
  - Pickerel River
  - Pretty River
  - St. Marys River
    - Garden River
    - Bar River
  - Saugeen River
  - Seguin River
  - Serpent River
  - Spanish River
    - Agnes River
    - Aux Sables River
    - Vermilion River
  - Whitefish River
- Lake Ontario Watershed ( in order of ascent mainly from west to east)
  - Niagara River
  - Niagara Falls
    - Welland River
      - Black Creek (Niagara)
  - Jordan Harbour Watershed
  - Red Hill Creek (Niagara)
  - Burlington Bay Watershed
    - Sulphur
  - Bronte Creek
  - Sixteen Mile Creek (Toronto)
  - Credit River
  - Humber River
    - Black Creek (Toronto)
    - Emerson Creek
    - Jersey Creek
    - Rainbow Creek (Woodbridge)
      - Robinson Creek (Toronto)
    - West Humber River
    - East Humber River
  - Etobicoke Creek
    - Heart Lake (Toronto)
  - Mimico Creek
  - Toronto Harbour
    - Don River, Toronto
      - west branch Don River
      - Taylor Creek
      - east branch Don river
        Beaver Creek (Toronto)
  - Highland Creek
  - Rouge River
  - Duffins Creek
  - Ganaraska River
  - Trent-Severn Waterway
    - Trent River
      - Crowe River
    - Rice Lake Watershed
      - Otonabee River
    - Sturgeon Lake Watershed
      - Scugog River
        Layton River
        Nonquon River
      - Lake Chemong Watershed
    - Lake Simcoe Watershed
      - Beaverton River
      - Black River
      - Holland River
      - Maskinonge River
      - Talbot River
    - Severn River
  - Moira River
    - Black River
    - Clare River
    - Skootamatta River
  - Salmon River
  - Napanee River
  - Cataraqui River
  - Gananoque River
- Lake Superior Watershed
  - Pigeon River
    - Arrow River
    - Pine River
  - Kaministiquia River
    - Mission River
    - McKellar River
    - Whitefish River
    - Shebandowan River
    - Redhorse River
    - Bear River
    - Rat River Bay, Rat River
  - Aguasabon River, Long Lake
  - Neebing River
  - McIntyre River
  - Current River
  - Sturgeon River
  - Nipigon Strait, Nipigon Bay, Nipigon River,Lake Helen
    - Lake Nipigon Watershed
      - Windigo River
        Mud River
      - Ogoki River
      - Kopka River
      - Ombabika Bay
      - Ombabika River
      - Ogaman River
      - Blackwater River
  - Steel River
  - Pic River
  - Black River
  - White River
  - Pukaskwa River
  - Magpie River
  - Michipicoten River
  - Old Woman River
  - Baldhead River
  - Gargantua River
  - Sand River
  - Agawa River
  - Montreal River
  - Batchawana River
  - Goulais River
- Ottawa River Watershed
  - Ottawa River
    - Rigaud River
      - East Rigaud River
    - South Nation River
      - Castor River
        North Castor River
        Middle Castor River
        South Castor River
        East Castor River
      - Little Castor River
    - Rideau River
      - Jock River
      - Tay River
    - Carp River
    - Mississippi River
      - Indian River
      - Clyde River
        Little Clyde River
      - Fall River
    - Madawaska River
      - Opeongo River
      - York River
        Little Mississippi River
      - South Madawaska River
        Galipo River
        Crossbar River
      - North Madawaska River
    - Bonnechere River
      - Sherwood River
      - Pine River
      - Aylen River
    - Muskrat River
      - Indian River
    - Petawawa River
      - Barron River
      - Crow River
      - North River
      - Little Madawaska River
      - Nipissing River
        Tim River
    - Chalk River
    - Mattawa River
      - Amable du Fond River
      - Kaibuskong River
      - North River
    - Montreal River
      - Lady Evelyn River
- Saint Lawrence River Watershed
  - Saint Lawrence River
  - Raisin River