Four fire engines and 21 firefighters and officers were called to a fire at a house in Sudbourne Road, Brixton.
Part of the first floor of the property was damaged by fire.
The Brigade was called at 1332 and the fire was under control at 1418. Fire crews from Brixton, Clapham and West Norwood fire stations attended the scene.
The cause of the fire is accidental and believed to have been caused by a halogen heater.