M
- (District Municipality of Muskoka) Morinus
- (Rainy River District) Morson
- (District Municipality of Muskoka) Mortimers Point
- (Lennox and Addington County) Morven
- (Lennox and Addington County) Moscow
- (Perth County) Moserville
- (Middlesex County) Mossley
- (Perth County) Motherwell
- (United Counties of Leeds and Grenville) Motts Mills
- (Frontenac County) Mountain Grove
- (Simcoe County) Mountain View Beach
- (Oxford County) Mount Elgin
- (Wellington County) Mount Forest
- (Bruce County) Mount Hope
- (Peterborough County) Mount Julian
- (Perth County) Mount Pleasant
- (Hastings County) Mount Pleasant
- (Elgin County) Mount Salem
- (Simcoe County) Mount Stephen
- (Simcoe County) Mount St. Louis
- (Renfrew County) Mount St. Patrick
- (Elgin County) Mount Vernon
- (Wellington County) Mount View
- (Renfrew County) Mud Lake
- (Oxford County) Muir
- (Middlesex County) Mullifarry
- (Grey County) Mulock
- (Middlesex County) Muncey
- (Perth County) Munro
- (Ottawa) Munster