Police were called to Mutton Lane at 9.15pm, following reports of an assault.
Officers say the 14-year-old sustained a stab wound after an altercation took place near Furzefield Leisure Centre.
The boy was taken to Barnet General Hospital by the ambulance service, who attended the scene in Mutton Lane.
Detectives from the Hertsmere Local Crime Unit, which is investigating the case, are appealing for witnesses and information.
Anyone who saw what happened, or the events prior to or after it, should contact Herts police on 101, quoting reference ISR 730 of June 11.
You can also report information online at herts.police.uk/Report.