The original hospital on the site was the Wellhouse Hospital which was opened by Viscount Hampden, the Lord Lieutenant of Hertfordshire, in November 1920. It was renamed Barnet General Hospital in 1950.
The rebuilding of the hospital was procured under a Private Finance Initiative contract in 1999. The works were designed by the Percy Thomas Partnership and carried out by Bouygues at a cost of £54 million. They were completed in February 2002 and the new facilities were opened by the Princess Royal in February 2003. Facilities management services are provided by Ecovert.
The new facilities include accident and emergency care, intensive care, internal medicine, surgery, gynecology, orthopaedics, anesthetics, haematology, stroke medicine, dermatology, paediatrics and genito-urinary medicine.
Since July 2014, the hospital has been part of the Royal Free London NHS Foundation Trust along with Chase Farm Hospital.