Four fire engines and 21 firefighters and officers were called to a fire at a block of flats in Portal Way, North Acton.
Part of a flat on the third floor of the building was damaged by fire. One woman left the property before the arrival of the Brigade and was taken to hospital suffering from smoke inhalation by London Ambulance Service crews.
The Brigade was called at 1137 and the fire was under control at 1206. Fire crews from Acton, Park Royal, Willesden and Ealing fire stations attended the scene.
The cause of the fire is currently unknown.