Four fire engines and 25 fire fighters were called to a fire at a house converted into flats on Rosendale Road, SE21.
Half of the third floor of the four storey semi-detached house was damaged by the fire.
One woman left the property before the Brigade arrived and taken to hospital by the London Ambulance Service.
The Brigade was called at 1809 and the fire was under control by 1919. Fire crews from West Norwood, Brixton and Forest Hill fire stations were in attendance.
The cause of the fire is undetermined.