Four fire engines and around 25 firefighters were called to a fire at a house on Brook Avenue in Wembley.
Half of the ground and first floors of the semi-detached house were damaged by fire. One man left the building before the Brigade arrived. He was treated on scene by London Ambulance Service crews.
The Brigade was called at 2249 and the fire was under control by 0000. Fire crews from Wembley, Willesden and Park Royal fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.