Two fire engines and 10 firefighters and officers were called to a fire at a restaurant with flats above on Greenford Road in Greenford.
Part of the ground floor extension was damaged by fire.
A resident in a neighbouring property called the Brigade after hearing a smoke alarm sounding in the restaurant.
Six residents in the flats above the restaurant were assisted from the building by the Brigade via an internal staircase. There were no reports of any injuries.
The Brigade was called at 0318 and the fire was under control at 0409. Fire crews from Northolt Fire Station attended the scene.
The cause of the fire is believed to be accidental and started in a fat fryer.