Four fire engines and around 25 firefighters tackled a flat fire on Greystead Road in Forest Hill.
A small part of a five-roomed flat on the second floor of a residential block under refurbishment was damaged by fire. Firefighters wearing breathing apparatus rescued a woman from the living room of the property who was taken to hospital.
The Brigade was called at 1322 and the fire was under control by 1420. Fire crews from Forest Hill, New Cross, Lewisham and Lee Green fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.