Ten fire crews from across the Black Country were called to the blaze in Alma Street, Heath Town.
West Midlands Fire Service said the building was "100% involved in fire".
Nearby residents were advised to keep windows and doors closed because of the large amount of smoke in the area.
10 Crews from across the Black Country are dealing with a severe factory fire on Alma Street, Heath Town, Wolverhampton. The building is 100% involved in fire. Due to large amounts of smoke in the area, residents are advised to keep windows and doors closed.— West Midlands Fire Service (@WestMidsFire) April 2, 2018
Those who reside in Heath Town back at home: Massive Factory Fire on Alma Street (at the top of Inkerman on the left hand side) - building involved completely ablaze so keep ALL Windows Closed if you live nearby. #Wolverhampton https://t.co/DgSDxw5d5u— Kashmire DS Hawker 🐺🌹 (@KDSHawker) April 2, 2018