Which province is Canada's most populous?

Ontario is Canada's most populous province, home to about 16 million people in 2025 according to Statistics Canada quarterly population estimates. The province accounts for roughly 39 per cent of Canada's national population of about 41 million. Toronto, the provincial capital, is Canada's largest city and the principal metropolitan centre of the country, with a Census Metropolitan Area population of about 7 million. Other major Ontario centres include Ottawa (Canada's national capital), Hamilton, London, Kitchener-Cambridge-Waterloo, and Windsor.

Ontario joined Canadian Confederation on July 1, 1867 as one of the four founding provinces along with Quebec, New Brunswick, and Nova Scotia. The province extends from the Great Lakes north to Hudson Bay and James Bay, covering 1,076,395 square kilometres. The southern population belt along Lakes Ontario and Erie (the Quebec City to Windsor Corridor) holds most of the province's economic activity, while the Canadian Shield north of the Great Lakes is sparsely populated and forested.

Ontario is the heart of Canada's manufacturing sector, with the Windsor-to-Oshawa automotive corridor producing about 1.4 million vehicles a year for Ford, General Motors, Stellantis, Honda, and Toyota. The province also hosts Bay Street, Canada's principal financial district, the Toronto Stock Exchange, and the head offices of the Big Five chartered banks. The Toronto-Waterloo Innovation Corridor is the second-largest technology cluster in North America. Ontario's gross domestic product was about $1.1 trillion in 2024, roughly 38 per cent of national GDP.

Ontario's geography ranges from the Great Lakes shoreline (the longest of any Canadian province) through the Niagara Escarpment, the Canadian Shield, the Hudson Bay Lowlands, and the James Bay coast. The province has more than 250,000 lakes and includes parts of Lakes Superior, Huron, Erie, and Ontario. The provincial flower is the white trillium, and the provincial bird is the common loon. The Ontario Legislative Assembly sits at Queen's Park in Toronto.