Police are appealing for witnesses to the incident, which happened on Clotherholme Road, near the junction of Aislabie Garth.
The 14-year-old pedestrian was hit by a car as he walked to school at around 8.45am.
Paramedics also attended and he has been taken to hospital with serious injuries. His condition is currently described as critical. His family has been informed and is currently with him in hospital.
The road has been closed to allow emergency services to deal with the incident and carry out investigations. It is likely to stay closed for several hours and drivers are urged to use alternative routes to prevent congestion in the area.
Anyone who witnessed the incident, which involved a silver car, is urged to contact North Yorkshire Police on 101. Please select option 2 and ask for Rob Roberts. You can also email Traffic Constable Roberts at Rob.Roberts@northyorkshire.pnn.police.uk
Please quote incident reference NYP-11122017-0090 when sharing information.