The boy was in the backseat of a Hyundai Getz when it crashed into a parked truck and trailer on Christie Street in St Marys at 3.20am on Friday.
He suffered critical injuries and was taken to Westmead Children’s Hospital, where he died overnight.
The driver of the car, a 38-year-old woman, also suffered critical injuries and remains in hospital.
An investigation is now underway into the circumstances surrounding the crash.
Anyone with information on the crash is urged to contact police.
