Four fire engines and around 25 firefighters tackled a flat fire on Church Road in Isleworth.
Part of a four-roomed flat on the third floor of the building was damaged by fire. Around 15 people were led to safety as a precaution. A man was taken to hospital by London Ambulance Service crews.
The Brigade was called at 0934 and the fire was under control by 1054. Fire crews from Heston, Chiswick and Feltham fire stations attended the scene.
The fire is believed to have been accidental and caused by hot works.