Six fire engines and 35 firefighters and officers were called to a fire at a restaurant with flats above in High Road, Willesden.
Part of the ground floor was alight and ducting from the ground floor to the roof were also alight.
Station Manager Steve Chesson, who was at the scene, said: "Crews were faced with a well developed fire when they arrived at the scene.
"They worked hard to bring the fire under control."
The Brigade's 999 Control Officers took 12 calls to the fire.
The Brigade was called at 1352 and the fire was under control at 1638. Fire crews from Willesden, West Hampstead, North Kensington, Park Royal and Clapham fire stations attended the scene.
The cause of the fire is under investigation.