Six fire engines and around 40 firefighters were called to a fire at a shop with flats above on Edgware Road in Marble Arch.
A small part of the shop was damaged by the fire. Crews evacuated around 40 people from the flats as a precaution. There were no reports of any injuries.
The Brigade was called at 0632 and the fire was under control at 0820. Fire crews from Paddington, Soho, Euston and Chelsea fire stations attended the scene.
The Brigade's fire investigation team believe the fire was caused by an electrical fault in a display cabinet fluorescent light fitting.