Six fire engines and around 40 firefighters were called to a fire on Vicarage Park in Plumstead.
A car workshop was destroyed by fire. Two people left the building before firefighters arrived and there were no reports of any injuries.
The Brigade received the first of 11 calls at 0606 and Control Officers mobilised crews from Plumstead, East Greenwich, Eltham, Erith and Lee Green fire stations, as well as a 32-metre turntable ladder from East Greenwich Fire Station, to the scene.
The fire was brought under control by 0818.
The cause of the fire has been recorded as undetermined due to the unsafe structure of the building.