Four fire engines and around 25 firefighters were called to a flat fire on Courtfield Road in South Kensington.
Part of a three-roomed flat on the lower ground floor of a converted house was damaged by fire. There were no reports of any injuries.
The Brigade was called at 2249 and the fire was under control by 0006. Fire crews from Kensington, Chelsea, Hammersmith and Fulham fire stations attended the scene.
The fire is believed to have been accidental and caused by hot works carried out on the property.