Four fire engines and around 25 firefighters were called to a flat fire on Western Avenue in Acton.
Half of a four-roomed flat on the second floor of the building was damaged by fire. One man was taken to hospital by London Ambulance Service crews.
Sub Officer Amanda Glover, who was at the scene, said: “There was heavy smoke in the area and two lanes were closed on Western Avenue whilst crews worked swiftly to make the scene safe.
“A man left the affected flat before the Brigade arrived and was then led to safety from the second floor.”
The Brigade's 999 Control Officers took 32 calls to the fire.
The Brigade was called at 1649 and the fire was under control by 1736. Fire crews from Park Royal, Acton, Willesden and Chiswick fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and the Metropolitan Police Service.