The North-Western Territory at its greatest extent, 1859

The North-Western Territory was a region of British North America until 1870. Named for where it lay in relation to Rupert's Land, the territory at its greatest extent covered what is now Yukon, mainland Northwest Territories, northwestern mainland Nunavut, northwestern Saskatchewan, northern Alberta and northern British Columbia.

It is obscure when exactly Great Britain first asserted sovereignty over the territory; however, after France accepted British sovereignty over Rupert's Land by the Treaty of Utrecht (1713), Great Britain was the only European power with practical access to that part of the continent. The Hudson's Bay Company, despite the royal charter assigning only Rupert's Land to the company, had long used the region as part of its trading area before the governance of the North-Western Territory was explicitly assigned to the company in 1859. Unlike in Rupert's Land, land title in the North-Western territory belonged to the Crown instead of the company. The British made virtually no effort to assert sovereignty over the Aboriginal peoples of the area. In accordance with the Royal Proclamation of 1763, large-scale settlement by non-Aboriginal people was prohibited until the lands were surrendered by treaty.

In 1862 during the Cariboo Gold Rush , part of the North-Western Territory became the Stickeen Territory to enable easier governance from the west coast. The following year, part of the area returned to the North-Western Territory when boundaries were adjusted and British Columbia was extended to the north. In 1868, shortly after Canadian Confederation, the Hudson's Bay Company agreed to surrender its vast territories to the new dominion. However, it was not until July 15, 1870, that the transfer to Canada was made. On that date the North-Western Territory became part of the newly created Northwest Territories.