| Oakland | Brandon | MANITOBA |
| Oakland | LUNENBURG | NOVA SCOTIA |
| Oakland | OXFORD (South/Sud) | ONTARIO |
| Oakley | ONTARIO (North/Nord) | ONTARIO |
| Oakville (Town/Ville) | HALTON | ONTARIO |
| Ochre River | MACDONALD | MANITOBA |
| Ochre River | MARQUETTE | MANITOBA |
| Odanah | MARQUETTE | MANITOBA |
| Ogilvie Post (Yukon) | UNORGANIZED TERRITORIES/TERRITOI | THE TERRITORIES |
| Ohio | SHELBURNE & QUEENS | NOVA SCOTIA |
| Ohio | YARMOUTH | NOVA SCOTIA |
| Ohlen | ASSINIBOIA (East/Est) | THE TERRITORIES |
| Oil Springs (Village) | LAMBTON (East/Est) | ONTARIO |
| Okotoks | ALBERTA | THE TERRITORIES |
| Old Wives Lake | ASSINIBOIA (West/Ouest) | THE TERRITORIES |
| Olden | ADDINGTON | ONTARIO |
| Olds | ALBERTA | THE TERRITORIES |
| Oliver | ALGOMA | ONTARIO |
| Olsen | ALBERTA | THE TERRITORIES |
| Omemee (Village) | VICTORIA (South/Sud) | ONTARIO |
| Oneida | HALDIMAND & MONCK | ONTARIO |
| Oneida (Indian reserve/Réserve indienne) | HALDIMAND & MONCK | ONTARIO |
| Onion Lake | SASKATCHEWAN | THE TERRITORIES |
| Onondaga | BRANT (South/Sud) | ONTARIO |
| Onslow (North/Nord) | PONTIAC | QUEBEC |
| Onslow (South/Sud) | PONTIAC | QUEBEC |
| Ops | VICTORIA (South/Sud) | ONTARIO |
| Orangeville (Town/Ville) | WELLINGTON (Centre) | ONTARIO |
| Orford | ELGIN (West/Ouest) | ONTARIO |
| Orford | SHERBROOKE | QUEBEC |
| Orillia | SIMCOE (East/Est) | ONTARIO |
| Orillia (Town/Ville) | SIMCOE (East/Est) | ONTARIO |
| Ormstown (Village) | CHÂTEAUGUAY | QUEBEC |
| Oro | SIMCOE (East/Est) | ONTARIO |
| Osgoode | RUSSELL | ONTARIO |
| Oshawa (Town/Ville) | ONTARIO (South/Sud) | ONTARIO |
| Osler | SASKATCHEWAN | THE TERRITORIES |
| Osnabruck | CORNWALL & STORMONT | ONTARIO |
| Oso | ADDINGTON | ONTARIO |
| Osprey | GREY (East/Est) | ONTARIO |
| Otonabee | PETERBOROUGH (East/Est) | ONTARIO |
| Ottawa (City/Cité) By (Ward/Quartier) | OTTAWA (City/Cité) | ONTARIO |
| Ottawa (City/Cité) Central (Ward/Quartier) | OTTAWA (City/Cité) | ONTARIO |
| Ottawa (City/Cité) Dalhousie (Ward/Quartier) | OTTAWA (City/Cité) | ONTARIO |
| Ottawa (City/Cité) Ottawa (Ward/Quartier) | OTTAWA (City/Cité) | ONTARIO |
| Ottawa (City/Cité) St. George (Ward/Quartier) | OTTAWA (City/Cité) | ONTARIO |
| Ottawa (City/Cité) Victoria (Ward/Quartier) | OTTAWA (City/Cité) | ONTARIO |
| Ottawa (City/Cité) Wellington (Ward/Quartier) | OTTAWA (City/Cité) | ONTARIO |
| Ottawa (East/Est) (Village) | CARLETON | ONTARIO |
| Otthon | ASSINIBOIA (East/Est) | THE TERRITORIES |
| Ouiatchouan | CHICOUTIMI & SAGUENAY | QUEBEC |
| Outremont (Town/Ville) | JACQUES-CARTIER | QUEBEC |
| Owen Sound (Town/Ville) | GREY (North/Nord) | ONTARIO |
| Owen Sound (Town/Ville) | GREY (North/Nord) | ONTARIO |
| Oxbow | ASSINIBOIA (East/Est) | THE TERRITORIES |
| Oxford | LEEDS & GRENVILLE (North/Nord) | ONTARIO |
| Oxford (East/Est) | OXFORD (South/Sud) | ONTARIO |
| Oxford (North/Nord) | OXFORD (South/Sud) | ONTARIO |
| Oxford (West/Ouest) | OXFORD (South/Sud) | ONTARIO |