The fire broke out about 10.45am at Modus Architectural Lighting, in Wagener Place, a short distance from the extensive St Lukes shopping mall.
Fire Service northern communications shift manager Colin Underdown said the large building had been well ablaze and had to be tackled by a unit with specialised extension equipment which could work above the flames.
Up to 12 fire crews remained at the scene dampening down hotspots, he said. Smoke billowed across Auckland for several kilometres at the height of the blaze.
Police reported significant traffic congestion in the area near the mall as a result of road closures. The business was flanked by warehouses, including Toy Warehouse and Storage King, with at least two apartments nearby.
