Four fire engines and around 25 firefighters tackled a fire at a block of flats on Blackhorse Road in Walthamstow.
Half of a three-roomed flat on the second floor of the three-storey building was damaged by fire. There were no reports of any injuries.
The fire is believed to have been accidental and caused by an electrical fault in an air fryer.
A London Fire Brigade spokesperson said: "Fires are more likely to start in the kitchen than any other room in the home.
“It’s really important that you always check air fryers and other appliances are turned off and unplugged when not in use, unless they’re designed to be left on, like your fridge or freezer.
“Keep clutter to a minimum on your kitchen work surfaces especially near air fryers, toasters and hobs as they can accidentally switch them on or catch fire.”
The Brigade was called at 1115 and the fire was under control 1202. Crews from Homerton, Tottenham, and Stoke Newington fire stations attended the scene.