Eight fire engines and around 60 firefighters tackled a fire on the A406 North Circular in Arnos Grove.
The ground floor and staircase of a two-storey building, made up of shops and homes, was destroyed by fire. There have been no reports of any injuries.
One of the Brigade's 32 metre turntable ladders was used as an observation tower.
The incident caused significant traffic delays for drivers travelling eastbound on the A406 North Circular road between the junctions of Bounds Green Road and Powys Lane. Motorists were advised to find alternative routes whilst the incident was ongoing.
The Brigade was called at 1955 and the fire was brought under control by 0037. Crews from Southgate, Finchley, Hornsey, Tottenham and surrounding fire stations are at the scene.
The cause of the fire is being investigated by the Brigade and Metropolitan Police.