Six fire engines and around 40 firefighters were called to a fire at a terraced house converted into flats on Brownlow Road in Harlesden.
Half of the ground and first floors and half of a loft conversion and the roof were damaged by the blaze. There were no reports of any injuries.
The Brigade was called at 0828 and the fire was under control by 1125. Fire crews from Willesden, Park Royal, Wembley and surrounding fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.