Four fire engines and around 25 firefighters were called to a flat fire on Guildford Street in Bloomsbury.
Half of a five-roomed flat on the lower ground floor of a converted mid-terraced house was damaged by fire. One man left the building before the Brigade arrived and was taken to hospital after suffering from smoke inhalation.
The fire is believed to have been accidental and caused by the unsafe use of smoking materials.
A London Fire Brigade spokesperson said: “We’d rather you didn’t smoke at all, but if you are a smoker, it’s absolutely vital you ensure your cigarette is completely out when you’ve finished smoking it.
“If you don’t, you risk causing a fire which could not only destroy your home, but also cost you your life.
“There were no working smoke alarms fitted in the property, so this is also a reminder to make sure you have working smoke alarms in every room where a fire could start in your home, plus a heat alarm in the kitchen. Make sure to test them regularly.”
The Brigade was called at 2236 and the fire was under control by 2344. Fire crews from Soho and Islington fire stations attended the scene.