Four fire engines and 21 firefighters and officers were called to a fire at a house in Pretoria Road, Streatham.
Part of the first floor of a two-storey house was damaged by fire. A 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 1229 and the fire was under control at 1315. Fire crews from Tooting, Norbury and West Norwood fire stations attended the scene.
The cause of the fire is under investigation.