York was a town and second capital of the colony of Upper Canada. It is the predecessor to the old city of Toronto (18341998). It was established in 1793 by Lieutenant-Governor John Graves Simcoe as a "temporary" location for the capital of Upper Canada, while he made plans to build a capital near today's London, Ontario. Simcoe renamed the location York after Prince Frederick, Duke of York and Albany, George III's second son. Simcoe gave up his plan to build a capital at London, and York became the permanent capital of Upper Canada on February 1, 1796. That year Simcoe returned to Britain and was temporarily replaced by Peter Russell.

The original townsite was a compact ten blocks near the mouth of the Don River and a garrison was built at the channel to Toronto Harbour. Government buildings and a law court were established. Yonge Street was built, connecting York to the Holland River to the north. To the east, Kingston Road was built to the mouth of the Trent River. In 1797, the town site was expanded to the west to allow for public buildings and expansion. One of the new area's public functions, a public market, was started in 1803. It continues today as St. Lawrence Market.

The garrison was attacked during the War of 1812. As the British Army retreated, it blew up the garrison, leading to the death of numerous American soldiers and the American general commanding the attack. The victorious Americans sacked the town and burned down the government buildings. The Americans chose not to occupy the town and the British eventually returned without conflict. A retribution attack was made on the American capital of Washington.

After the war was over, the town continued to grow, expanding to the west, leaving the original town site, a less desirable location, somewhat undeveloped. A new parliament building was erected, near the original location, but this burned down and a new building was built in the new lands to the west. A permanent fort, Fort York, was built on the site of the garrison. Dundas Street was built to connect York to towns to the west. In the 1820s, the town experienced a surge of immigrants, expanding from 1,000 residents to over 9,000 by the time the town was incorporated as the City of Toronto in 1834. During its existence, the town did not have its own government; it was governed by the province of Upper Canada, with a mix of elected officials and an aristocracy known as the Family Compact controlling the government. By 1830, this led to an ongoing political conflict, which would later lead to the 1837 Upper Canada Rebellion.

The Province of Upper Canada (French: province du Haut-Canada) was a part of British Canada established in 1791 by the Kingdom of Great Britain, to govern the central third of the lands in British North America, formerly part of the Province of Quebec since 1763. Upper Canada included all of modern-day Southern Ontario and all those areas of Northern Ontario in the Pays d'en Haut which had formed part of New France, essentially the watersheds of the Ottawa River or Lakes Huron and Superior, excluding any lands within the watershed of Hudson Bay. The "upper" prefix in the name reflects its geographic position along the Great Lakes, mostly above the headwaters of the Saint Lawrence River, contrasted with Lower Canada (present-day Quebec) to the northeast.

Upper Canada was the primary destination of Loyalist refugees and settlers from the United States after the American Revolution, who often were granted land to settle in Upper Canada. Already populated by Indigenous peoples, land for settlement in Upper Canada was made by treaties between the new British government and the Indigenous, exchanging land for one-time payments or annuities. The new province was characterized by its British way of life, including bicameral parliament and separate civil and criminal law, rather than mixed as in Lower Canada or elsewhere in the British Empire. The division was created to ensure the exercise of the same rights and privileges enjoyed by loyal subjects elsewhere in the North American colonies. In 1812, war broke out between Great Britain and the United States, leading to several battles in Upper Canada. The United States attempted to capture Upper Canada, but the war ended with the situation unchanged.

The government of the colony came to be dominated by a small group of persons, known as the "Family Compact", who held most of the top positions in the Legislative Council and appointed officials. In 1837, an unsuccessful rebellion attempted to overthrow the undemocratic system. Representative government would be established in the 1840s. Upper Canada existed from its establishment on 26 December 1791 to 10 February 1841, when it was united with adjacent Lower Canada to form the Province of Canada.