Government House was the official residence of the lieutenant governor of Upper Canada and Ontario, Canada. Four buildings were used for this purpose, none of which exist today, making Ontario one of four provinces not to have an official vice-regal residence.

The lieutenant governor of Ontario is the representative in Ontario of the monarch, who operates distinctly within the province but is also shared equally with the ten other jurisdictions of Canada, as well as the other Commonwealth realms and any subdivisions thereof, and resides predominantly in his oldest realm, the United Kingdom. The lieutenant governor of Ontario is appointed in the same manner as the other provincial viceroys in Canada and is similarly tasked with carrying out most of the monarch's constitutional and ceremonial duties. The current lieutenant governor of Ontario is Edith Dumont, sworn in on November 14, 2023.