Eight fire engines and around 60 firefighters were called to a fire at a hostel on Harrow Road in Kensal Green.
Over 200 people evacuated the five floor building before the Brigade arrived. Part of the ground floor of the building was damaged.
The Brigade was called at 2338 and the fire was under control at 0119. Fire crews from North Kensington, Wilesden, Park Royal, Paddington and West Hampstead attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.