Four fire engines and around 25 firefighters were called to a fire at a flat in Westbourne Park Road, Westbourne Green.
Part of a first floor flat was damaged by fire.
One woman was rescued by firefighters wearing breathing apparatus and she was treated for smoke inhalation before being taken to hospital by London Ambulance Service crews. Firefighters also rescued a dog and treated it at the scene for smoke inhalation.
The Brigade was called at 0137 and the fire was under control at 0230. Fire crews from North Kensington, Kensington and Paddington fire stations attended the scene.
The cause of the fire is under investigation.