Five fire engines and around 35 firefighters were called to a maisonette fire on Inville Road in Elephant and Castle.
A mattress in a communal staircase between the fifth and sixth floors of the building was destroyed by fire. There were no reports of any injuries.
The Brigade was called at 1412 and the fire was under control by 1523. Fire crews from Peckham, Dockhead, Dowgate and Soho fire stations attended the scene.
The cause of the fire is under investigation