Three fire engines and 14 firefighters and officers were called to a fire at a house converted into flats in Chantry Road in Brixton.
The kitchen of the ground floor flat was damaged by fire.
One man was rescued by firefighters wearing breathing apparatus. He was treated at the scene for smoke inhalation by London Ambulance Service crews.
The cause of the fire is believed to be due to a gas hob igniting clothing.
The Brigade was called at 1144 and the fire was under control at 1211. Fire crews from Brixton and Clapham fire stations attended the scene.