Four fire engines and around 25 firefighters were called to a flat fire on Boundfield Road in Catford.
Part of a two-roomed flat on the ground floor of the building was damaged by fire. Firefighters wearing breathing apparatus rescued a woman from the affected flat who was taken to hospital by air ambulance, where she sadly later died.
The Brigade was called at 2034 and the fire was under control by 2140. Fire crews from Lee Green, Lewisham, Bromley and Forest Hill fire stations attended the scene.
The cause of the fire remains under investigation.