The fire broke out on Slaney Road, in Pleck, just after midnight and was described as 'severe' by crews.
The cause of the latest blaze remains unknown but an investigation was today under way.
A spokesman for West Midlands Fire Service said: "We still have two fire crews and an aerial platform at the scene. Firefighters continue to damp down hotspots and are likely to be there for a number of hours yet.
"The cause has yet to be determined."
A spokeswoman for West Midlands Ambulance Service added: "We were called by the fire service at 1.12am to a property fire on Slaney Road, Walsall.
"One paramedic officer attended but no patients were found."
Residents were urged to close their windows and doors as smoke billowed from the derelict building.
Crews were previously called to fires at the building at the start of November and again back in July, both believed to have been started deliberately.