Four fire engines and 21 firefighters and officers were called to a fire at a derelict clothing factory in Waddon Marsh Way, Croydon.
A small part of the roof and ground floor of the building were damaged by the fire.
The Brigade was called at 0541 and the fire was under control at 0639. Fire crews from Croydon, Wallington, Norbury and Woodside fire crews attended the scene.
The cause of the fire is under investigation.