Four fire engines and 21 firefighters and officers were called to a flat fire on Brunswick Road in Sutton on Saturday afternoon (14 October).
The fire gutted a flat on the ground floor of the three storey block and a woman was treated by London Ambulance Service for smoke inhalation.
The Brigade was called at 1645 and the fire was under control by 1738. Crews from Croydon, Norbury and Tooting fire stations were at the scene.
The cause of the fire is under investigation.