U
- (Simcoe County) Udney
- (District Municipality of Muskoka) Ufford
- (District Municipality of Muskoka) Ullswater
- (Frontenac County) Ungava
- (United Counties of Leeds and Grenville) Union
- (Oxford County) Uniondale
- (Simcoe County) Uptergrove
- (Ottawa) Urbandale
- (Haliburton County) Ursa
- (Durham) Utica
- (Simcoe County) Utopia
- (Durham) Uxbridge