The 41-year-old victim was travelling on Joe Shuster Way near King and Dufferin streets around 6:30 a.m. when his 1989 Ford Taurus failed to negotiate a right turn properly, "slid through a construction barrier and into a pit," said Const. Clint Stibbe, a spokesman for the traffic services division.
The man was extracted from the vehicle and airlifted away after several hours.
Stibbe said the construction pit at 38 Joe Shuster Way was about 21 feet deep.
"Emergency personnel did find the individual, but were unable to confirm whether or not he was wearing a seatbelt," Stibbe said, adding that the victim has been identified but that police are still in the process of notifying the next of kin.
Police said they would have trouble removing the car from the pit due, in part, to rainy weather.
The cause of the accident is still under investigation.