The incident happened just before midnight on Saturday, when a Toyota Celica was heading north on Marilake Drive, near Midland Avenue and Highway 401.
Staff Sgt. Dave Sterling said the driver lost control and hit a parked car.
"As a result of the impact, the vehicle rolled and the driver was ejected from the vehicle," Sterling told CBC News.
The 24-year-old man driving the vehicle was taken to a trauma centre, but he was pronounced dead at 12:37 a.m. Sunday.
Sterling said "speed is certainly a factor" in the crash, though investigators are still trying to piece together what happened.
The name of the deceased has not yet been released.