Morton Grove police said the homeowner saw two male suspects breaking into his vehicle, parked in the 7300-block of Palma Lane, around 2:45 a.m.
A homeowner tried to confront the suspects, police said, but they battered him and shot him in the leg before fleeing the scene in a dark-colored sedan.
The victim was taken to a local hospital in stable condition.
The Morton Grove Police Department asked anyone with information to call them at 847-470-5200.
Further information was not immediately available.