Six fire engines and around 40 firefighters tackled a blaze at a block of flats in Craven Avenue, Ealing.
A flat on the second floor was badly damaged by fire and a small part of the outside of the building was also damaged.
One man left the building before the arrival of the brigade and another was rescued by crews wearing breathing apparatus. Both men were taken to hospital by London Ambulance Service. Sadly, the man who was rescued later died in hospital.
The Brigade was called at 0527 and the fire was under control by 0722. Crews from Ealing, Acton, Southall, Chiswick and Wembley fire stations attended the incident.
The cause of the fire is under investigation.