Four fire engines and around 25 firefighters tackled a flat fire on Vestry Road in Camberwell.
Most of a four-roomed flat on the second floor of a residential block was damaged by fire. The window of a third-floor flat was also destroyed, along with part of the guttering and fascia. There were no reports of any injuries.
The Brigade's 999 Control Officers took more than 10 calls to the blaze.
The Brigade was called at 0743 and the fire was under control by 0846. Fire crews from Peckham, Brixton, New Cross and Lambeth fire stations attended the scene.
The cause of the fire is under investigation.