Two fire engines and 10 firefighters and officers were called to a fire at a house in Gloucester Road, Croydon.
Part of the ground floor was damaged by fire. One woman was rescued from the first floor by crews wearing breathing apparatus. She was taken to hospital by London Ambulance Service crews suffering smoke inhalation.
The Brigade was called at 0657 and the fire was under control at 0802. Fire crews from Woodside and Croydon fire stations attended the scene.
The cause of the fire is under investigation.