Four fire engines and around 25 firefighters were called to a fire at a maisonette in Galatea Square in Peckham.
Half of the first floor was damaged by fire. One man was assisted from the property by a member of the public before the arrival of the Brigade.
The Brigade was called at 1528 and the fire was under control at 1655. Fire crews from New Cross, Brixton, Old Kent Road and Lewisham fire stations attended the scene.
The cause of the fire is under investigation.