Four fire engines and around 25 firefighters were called to a flat fire on Frampton Road in St Johns Wood.
Half of a ground floor flat was damaged by the blaze. A woman and a child left the property before the Brigade arrived.
The cause of the fire is believed to be the failure of a tablet battery while in was charging.
The Brigade was called at 2126 and the fire was under control by 2245. Fire crews from Paddington, Euston and North Kensington fire stations were at the scene.