Four fire engines and around 25 firefighters were called to a fire at a derelict office block of three floors on West Hendon Broadway in Colindale.
A small part of the second floor was damaged by fire. There are no reports of any injuries.
The Brigade was called at 1821 and the fire was under control at 1927. Fire crews from Hendon, West Hampstead and Willesden fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and Metropolitan Police Service.