York Regional Police were called to the area of Major Mackenzie Drive East and Cedar Avenue, east of Yonge Street, around 9:15 p.m. for a collision.
They arrived to find a female pedestrian who had been struck by the driver of a vehicle. She was taken to hospital, where she died from her injuries.
The police are now looking for the driver, who did not stay at the scene and fled in an unknown direction.
The driver is believed to be operating a black 2009-2011 Honda Civic with a loud exhaust, police said.
They added that the vehicle sustained damage to the front end and windshield.
Police closed roads in the area as they investigated the crash.