Four fire engines and 21 firefighters and officers were called to a fire at a delivery office and workshop in Regis Road in Kentish Town.
A vehicle inside the workshop was destroyed by fire. One man suffered smoke inhalation and was treated at the scene by London Ambulance Service.
Around 25 people left the building before the arrival of the Brigade.
The Brigade was called at 1152 and the fire was under control at 1329. Fire crews from Kentish Town, Holloway and Euston fire stations attended the scene.
The cause of the fire is under investigation.