Six fire engines and around 40 firefighters were called to a flat fire on Thomas Lane in Catford.
Most of a flat on the sixth floor of a seven-storey block was damaged by the fire. One man left the building and was taken to hospital suffering smoke inhalation by London Ambulance Service crews.
Station Commander Jim Ryan, who was at the scene, said: “There was a lot of smoke visible from the outside of the building and our 999 Control Officers took five calls to the fire.
“Crews worked quickly to bring the blaze under control.
“Some areas of the flat suffered minimal damage as the doors into the rooms had been closed.
"It’s always a good idea to shut internal doors as in the event of a fire this can prevent further damage and limit smoke spread.”
The Brigade was called at 2337 and the fire was under control by 0057. Fire crews from Lewisham, Forest Hill, Deptford, New Cross and surrounding fire stations were at the scene.
The cause of the fire has been recorded as undetermined.