Boksburg SAPS station commander Col Biggs Govender said the boy was stabbed in the stomach.
He was taken to the Union Hospital where he was operated on and is in stable condition.
The car was stolen in Trichards Road on May 17 during the evening and then recovered after a couple of hours near the Boksburg Prison.
The complainant told the police that he was with the child in the car when he suddenly noticed someone walking in the middle of the lane he was driving in.
“The complainant said he stopped to allow the pedestrian to cross but instead, the pedestrian produced a firearm, pointed at him and ordered him out of the car.
“A tussle followed and the next thing the complainant remembers he was waking up in the bush with his vehicle stolen and the child missing,” said Govender.