Fifteen fire engines and around 100 firefighters were called to a fire on an industrial estate on Watermead Way in Tottenham.
The fire involved a two-storey warehouse, used for vehicle maintenance. The warehouse was destroyed by fire, along with part of an adjoining building.
Around 20 vehicles in the workshop were destroyed by fire, with one vehicle on the forecourt also damaged, due to the heat from inside the warehouse.
There have been no reports of any injuries.
A London Fire Brigade spokesperson said: "Firefighters have worked extremely hard through the night to extinguish this fire. The amount of smoke being produced by this fire was significant and we advised people, particularly within the Haringey borough area, to continue to keep their windows and doors.
"Whilst most of the fire is now out, deep seated pockets of fire remain and we will maintain a presence on site through the morning.
"Road closures were in place on Watermead Way at the junction of Leeside Road and motorists faced some disruption during the morning rush hour."
The Brigade received the first of over 28 calls about the fire at 2251 and Control Officers mobilised crews from Edmonton, Enfield, Tottenham, Chingford, Walthamstow and surrounding fire stations to the scene.
Three 32-metre turntable ladders were also in attendance and deployed as water towers to help extinguish the fire from above. The Brigade's drone team were also used to provide the Incident Commander with a greater situational awareness of the incident.
The fire was brought under control by 0301.
The cause of the fire is under investigation.