Four fire engines and around 25 firefighters were called to a fire at a sports pavilion on Purley Way in Croydon.
A single storey sports pavilion was destroyed by the fire. There were no reports of any injuries.
The Brigade's 999 Control Officers took 12 calls to the blaze.
The Brigade was called at 1818 and the fire was under control by 1952. Fire crews from Purley, Croydon, Wallington and Norbury fire stations were at the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.