The man was found at a bus shelter on Victoria Park Avenue, north of Highway 401 before 3 a.m.
EMS rushed the man to Sunnybrook trauma centre where he later died.
It is unclear what caused his death.
Police were called at around 2:45 a.m. to reports of gunfire but found no evidence confirming that yet.
A section of the street has now been closed for the investigation and buses are being diverted.