Twelve fire engines and around 80 firefighters tackled a flat fire on Cadogan Square in Belgravia.
Part of the mansard roof of a mid-terraced block of flats was alight. Around 15 people left the building before the Brigade arrived. There are currently no reports of any injuries.
The Brigade’s 999 Control Officers took 22 calls to the blaze.
Station Commander Matt Cole, who was at the scene, said: “The fire was in the roof space of the building and crews worked incredibly hard to bring it under control.
“One of the Brigade’s 32-metre turntable ladders was used to get water on to the building externally from height.
“Cadogan Square is currently closed and there are severe delays, so please avoid the area where possible.
“Whilst the fire is now under control, crews are expected to remain on scene throughout the evening.”
The Brigade was called at 1346 and the fire was under control by 1632. Fire crews from Soho, Lambeth, Chelsea and surrounding fire stations attended the scene.
The cause of the fire is under investigation.