Peel Regional Police say the collision occurred Saturday night at the intersection of Crystalhill Drive and Castlemore Road.
The 69-year-old victim was crossing the road when he was struck by a vehicle making a right-hand turn from Crystalhill Drive onto Castlemore Road.
Police say the vehicle fled the scene without stopping.
The victim was first taken to a local hospital and later transferred to a trauma centre.
According to a news release that police issued Sunday morning, the victim remains in critical, but stable condition.
Witnesses have told police that the vehicle involved in the collision was a light-coloured minivan that was last seen heading westbound on Castlemore Road.
Police are appealing for any additional witnesses to contact them. Investigators can be reached at (905) 453-2121, ext. 3710.
Members of the public can also call Crime Stoppers at 1-800-222-8477 if they wish to provide information anonymously.