At the time of European contact in 1615, both Iroquoian and Algonquian-speaking peoples inhabited this area, but by 1700, an Ojibwa (Anishnabe) group known as the Mississaugas had flown south from Lake Huron and had steered the Iroquois south of Lake Ontario.

In 1793, Governor John Graves Simcoe settled the town of York, named for Prince Frederick, Duke of York and Albany. Simcoe chose the location, having faith that the new site would be less vulnerable to attack by the Americans, and constructed Fort York at the entrance of the town's natural harbor, which was sheltered by a long sand-bar peninsula. The settlement was clustered at the eastern end of the harbor back of the peninsula, today roughly Parliament Street & Front Street.

Grievously, in 1813, American invading force captured, plundered, and burnt down much of the city in the Battle of York during their five-day occupation. After the War, the number of settlers from Great Britain and Ireland steadily increased, with modest folks settling in the south. Georgina, in the north of York Township, attracted retired military officers who were old guard of the Napoleonic Wars and the War of 1812, was well as aristocratic families, wealthy merchants and English landholders who built stately manors and shaped estates. In 1912 five huge greenhouses were built in Richmond Hill to mature the centre of Canada's commercial rose-growing industry.