Four fire engines and around 25 firefighters were called to a shed alight on Penrith Place in Thurlow Park.
Most of a garden shed was damaged by the blaze and part of a nearby ground floor flat was also damaged. There were no reports of any injuries.
The Brigade's 999 Control Officers took 12 calls to the fire.
The Brigade was called at 1456 and the fire was under control by 1602. Fire crews from Tooting, Norbury and Peckham fire stations were at the scene.
The cause of the fire is under investigation.