Four fire engines and around 25 firefighters were called to a fire at a shop with flats above on Rotherhithe New Road in Bermondsey.
Half of a bedsit on the first floor of the building was damaged by fire. There were no reports of any injuries.
The Brigade was called at 2353 and the fire was under control by 0018 (Monday). Fire crews from Old Kent Road, Deptford, Dockhead and Peckham fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.