Four fire engines and around 25 firefighters were called to a flat fire on Grafton Road in Kentish Town.
A small part of a split-level flat on the second and third floor of the building was damaged by fire. Firefighters led one man to safety via the internal staircase who was taken to hospital by London Ambulance Service crews.
The Brigade’s Fire Investigators believe the fire was caused by an unattended candle.
Sub Officer Gregg Jules, who was at the scene, said: “Firefighters arrived to find a flat filled with smoke and led a man to safety who was in the corridor of the building.
“Crews ventilated the property and worked to make the scene safe.
“Candles, incense sticks and oil burners are one of the most common causes of fire. It’s really important that you never leave a candle unattended and keep them away from anything that can easily catch fire.
“You should also ensure they are in a heat-resistant holder and placed on a stable surface so they won’t be knocked over.”
The Brigade was called at 0028 and the fire was under control by 0304. Fire crews from Kensington, Kentish Town and Fulham fire stations attended the scene.