Twelve fire engines and around 80 firefighters were called to a fire at a warehouse on Wadsworth Road in Perivale.
A three-storey warehouse was destroyed by the fire. There were no reports of any injuries.
Station Manager Justin Coo, who is at the scene, said: "Crews remain on scene this morning (Thursday) and local road closures are still in place so we would advise motorists to avoid the area.
"Firefighters have worked hard throughout the night to stop the fire spreading to neighbouring buildings."
The Brigade's 999 Control Officers took 34 calls to the fire.
The Brigade was called at 2335 (Wednesday) and the fire was under control by 0626 (Thursday). Firefighters will remain on scene throughout the morning damping down. Fire crews from Wembley, Ealing, Acton, Southall, Stanmore, Park Royal and surrounding fire stations were at the scene.
The cause of the fire is under investigation.