Six fire engines and around 40 firefighters were called to a fire at an industrial estate on Manor Road in Erith.
Part of the ground floor and a small part of the roof of a single-storey commercial unit used as a car workshop was damaged by fire. The paint spray booth inside the workshop and the extraction system were destroyed by the blaze. Three people left the building before the Brigade arrived. There were no reports of any injuries.
The alarm was raised by a member of staff who smelt smoke and found the fire within the spray booth.
Station Commander Stephen Irvine, who was at the scene, said: "The fire is believed to have started in one of the commercial units on an industrial estate being used as a car body repair and spray workshop.
"Firefighters used a drone and thermal imaging camera to provide them with a birds eye view of the incident and identify remaining hot spots of fire."
The Brigade was called at 1453 and the fire was under control by 1743. Fire crews from Erith, Bexley and Plumstead fire stations attended the scene.
The Brigade's Fire Investigators believe the fire was caused by heat from the paint baking process igniting built up paint inside the spray booth.