Four fire engines and around 25 firefighters responded to a fire on Ibsley Gardens, Roehampton.
One man was rescued from the property by crews wearing breathing apparatus, and a second man had left the property before firefighters arrived on scene. Both were treated on scene by the London Ambulance Service before being taken to hospital.
The Brigade took the first of over 20 calls reporting the fire at 0142 and crews from Wandsworth, Fulham, Battersea and surrounding fire stations were sent to the scene. Firefighters were able to bring the fire under control by 0256.
The cause of the fire is under investigation by the Brigade's specialist Fire Investigation Team.