Firefighters were called to a home on Clark Avenue, west of Yonge Street, at about 3 p.m.
Six trucks and more than 30 firefighters were sent out to the scene.
The home, a vehicle and a tree on the property were damaged by the blaze, which remains under investigation.
The fire was out by the early evening, though firefighters were expected to remain at the scene for a couple of hours.
York Regional Police say that no one is believed to have been in the home when the blaze broke out.