When Europeans first stumbled through the snow into Ontario, several Aboriginal nations already called the region home. The Algonquin and Huron tribes had long occupied the southern portion of the province, but by the time European colonization took hold in the early 18th century, the Iroquois Confederacy (aka the Five Nations) held sway in the lands south of Georgian Bay and east to Québec. The Ojibwe occupied the lands north of the Great Lakes and west to Cree territory on the prairies (today's Alberta and Saskatchewan).

The first Europeans on the scene were 17th-century French fur traders, who established basic forts to facilitate trade links with the Mississippi River. With the arrival of the British Loyalists around 1775, large-scale settlement began. After the War of 1812, British immigrants arrived in larger numbers, and by the end of the 19th century Ontario's farms, industries and cities were rapidly developing. In the aftermath of both world wars, immigration from Europe boomed – Toronto has since evolved into one of the world's most multicultural cities.

An industrial and manufacturing powerhouse, Ontario is home to around 40% of Canada's population. Despite boom times in Alberta, Ontario remains the first choice of immigrants from across the globe, with solid employment prospects and Toronto's well-established immigrant support services proving a powerful draw.