Ten fire engines and 72 firefighters and officers were called to a fire at an industrial estate in Trout Road in West Drayton.
A car workshop unit on the estate was damaged by fire.
The Brigade's 999 Control Officers received 36 calls to the fire.
Station Manager Shaun Coltress, who is at the scene, said: “Crews worked hard to bring the fire under control. The fire was contained to the unit of origin but firefighters are likely to remain at the scene into this evening.”
The Brigade was called at 1136 and the fire was under control at 1628. Fire crews from Hillingdon, Hayes, Heathrow, Southall, Feltham and other surrounding fire stations attended the scene.
The cause of the fire is under investigation.