Six fire engines and around 40 firefighters tackled a fire at a building on Archway Road in Highgate.
Half of the first floor of the derelict building was damaged by the fire. There were no reports of any injuries.
The Brigade's 999 Control Officers received 25 calls about the incident. The fire was extinguished by crews wearing breathing apparatus.
The Brigade was called at 1501 and the fire under control was under control at 1613. Fire crews from Hornsey, Kentish Town, Holloway, West Hampstead and Finchley attended the scene.
The cause of the fire is under investigation.