Four fire engines and around 25 firefighters were called to a fire at a flat on Mottingham Road in Mottingham.
Most of a four-roomed flat on the first floor of a two-storey block was damaged by the fire. One man was assisted from an adjacent flat by crews wearing breathing apparatus. There were no reports of any injuries.
The Brigade was called at 1213 and the fire was under control by 1307. Fire crews from Eltham, Sidcup and Bromley fire stations were at the scene.
The cause of the fire is under investigation.