Four fire engines and around 25 firefighters were called to a fire on Stanley Road in Hounslow.
The front door to a ground floor flat was destroyed by the fire and part of the communal corridor was also damaged. One woman left the building before the Brigade arrived. There were no reports of any injuries.
The Brigade was called at 2259 and the fire was under control by 2359. Fire crews from Heston, Feltham and Twickenham fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.