Six fire engines and around 40 firefighters were called to a fire on Osterley Park Road in Southall.
Part of a room on the ground floor was destroyed by fire. One man was rescued by crews wearing breathing apparatus. He was suffering from smoke inhalation and taken to hospital by London Ambulance Service. No other injuries are reported.
The cause of the fire is believed to be due to unsafe use of smoking materials.
A London Fire Brigade spokesperson said: “If you smoke, it's important to ensure your cigarette is disposed of carefully by stubbing it out, preferably in an ash tray. If you smoke before bed, make sure your cigarette is fully out and never leave your lit cigarette unattended. Carelessly discarded cigarettes can easily start fires.”
The Brigade was called at 0341 and the incident was over by 0451. Fire crews from Southall, Heston, Hayes, Ealing and Hillingdon fire stations were in attendance.