Police said officers were called to the River North neighborhood's 0-100-block of East Ohio Street around 4 a.m.
Responding officers found an unresponsive 22-year-old man inside a vehicle.
The Chicago Fire Department responded to the scene to treat man, who had suffered unknown injuries, police said.
Police said the victim was pronounced dead on the scene. How he died was not immediately clear, and his identity was not immediately released.
Area Three detectives are conducting a death investigation.
Police did not immediately provide further information.