Four fire engines and 21 firefighters and officers were called to a fire at a block of flats in Harlesden Road, Willesden.
Part of a five-roomed flat on the sixth floor was damaged.
One man was rescued by crews wearing breathing apparatus. He was treated at the scene for smoke inhalation before being taken to hospital by London Ambulance Service crews.
The Brigade was called at 0921 and the fire was under control at 1030. Fire crews from Willesden, Park Royal, Wembley and North Kensington fire stations attended the scene.
The cause of the fire is under investigation.