The female was treated for smoke inhalation by paramedics from London Ambulance Service and was taken to hospital.
The blaze caused damage to the first floor of a flat in Perrin Road, Wembley, with thick heavy smoke spreading throughout the home.
Fire crews rushed in wearing breathing equipment and led the woman to safety via an internal staircase.
Firefighters from Wembley fire station battled with the flames for around 45 minutes before it was put out.
London Fire Brigade said they were called at 6.03pm and the fire was under control by 6.45pm.
The cause of the fire is under investigation.