Four fire engines and around 25 firefighters were called to a fire at student accommodation above a restaurant on New Cross Road in New Cross.
Solar panels on the roof were damaged by fire. Around 40 people left the building before the arrival of the Brigade. There were no reports of any injuries.
The fire was discovered by a member of the public who saw smoke and alerted staff members inside.
The Brigade was called at 1322 and the fire was under control by 1523. Fire crews from New Cross, Old Kent Road, Forest Hill and Deptford fire stations attended the scene.
The fire is believed to be accidental and caused by an electrical fault.