Four fire engines and around 25 firefighters tackled a fire at a single storey sports out building on Mayfield Road in Thornton Heath.
Part of the flat roof was damaged by the fire. There were no reports of any injuries.
Control Officers took the first of three calls at 1917 and mobilised crews from Norbury and Croydon fire stations to the scene. The incident was over for firefighters at 2120.
The cause of the fire has been recorded as undetermined.