Five fire engines and around 30 firefighters tackled a fire at a flat on Shepherd's Bush Green in Shepherd's Bush.
Most of a three-roomed flat on the fourth floor of a six-storey building was damaged by fire. One man was treated by firefighters before being taken to hospital by London Ambulance Service crews. Around 20 people left the building before firefighters arrived.
Road closures were put in place to allow emergency services to work safely.
The Brigade was called at 1008 and the fire was under control by 1140. Fire engines from Kensington, North Kensington, Fulham, Acton and Paddington fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and Metropolitan Police.