Twelve fire engines and around 80 firefighters were called to a fire at a scrap metal recycling yard on Manor Road in Erith.
Around 400 tonnes of scrap metal is affected by the fire.
Deputy Assistant Commissioner Richard Arnold, who is at the scene, said: "Crews worked hard throughout the morning to bring the fire at a scrap metal recycling yard under control.
"One of the Brigade's 32-metre turntable ladders was used at the scene as a water tower to tackle flames from height and one of the Brigade's fire boats was used to pump water from the Thames.
"Firefighters will remain at the scene for the next few hours to ensure any remaining fire is extinguished."
The Brigade's Control Officers took the first of 16 calls to the fire at 0456 and sent fire crews from Erith, Bexley, Plumstead, Sidcup and surrounding fire stations to the scene. The fire was brought under control at 1127.
The cause of the fire will be investigated by the Brigade's Fire Investigation Unit.