Four fire engines and around 25 firefighters tackled a flat fire on Harley Road in Harlesden.
Most of the ground floor flat in a two-storey mid terraced house converted into two flats was damaged by the fire.
A man suffering from smoke inhalation was rescued by the fire crews wearing breathing apparatus, he was treated on scene by the London Ambulance Service crews and taken to hospital by them.
The Brigade was called at 2345 and the fire was under control at 0053. Fire crews from Park Royal, Willesden, North Kensington and Hammersmith fire stations attended the scene.
The cause of the fire is under investigation.