Eight fire engines and around 60 firefighters were called to a fire at a house, used as a suspected cannabis factory, on Churchill Road in Willesden.
Half of the first floor of the two-storey, terraced house was damaged by fire and the loft space was destroyed by the blaze. There were no reports of any injuries.
Station Commander Neil Dickinson, who was at the scene, said: "The fire appears to have started on the first floor of the building and spread into the roof space of the house, where there was heavy smoke logging.
"Crews used cutting equipment to remove tiles from the roof and gain access to ensure the fire was under control.
"Firefighters remained on scene throughout the night, damping down remaining hot spots."
The Brigade was called at 0135 and the fire was under control by 0413. Fire crews from Willesden, North Kensington, West Hampstead, Park Royal and surrounding fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.