The youngster was taken to St George's Hospital in Tooting with serious injuries.
A woman has been arrested on suspicion of drink-driving after a five-year-old boy riding a bike was involved in a collision with a car.
The incident happened in Gole Road, Pirbright, at around 3.30pm on Tuesday, outside the Goal Farm golf club.
The young cyclist was taken to St George's Hospital in Tooting with serious injuries.
The driver of the car was also taken to hospital suffering from shock.
Police confirmed a woman in her 30s had been arrested on suspicion of drink-driving.
Anyone who saw the collision or the events surrounding it is asked to contact Surrey Police on 101 quoting reference P15004603.