The Scottish Fire and Rescue Service said crews were met with a “well-developed fire” when they went to the scene in High Street after the alarm was raised.
Nine fire appliances, including two height appliances, were still at the scene at 7am on May 4.
There were no reports of any injuries.
A Scottish Fire and Rescue Service spokesperson said: “We were alerted at 1:27am on Tuesday, May 4 to a report of a derelict building on fire at High St, Glasgow.
“Operations Control immediately mobilised four fire appliances to the scene. Firefighters were met with a well-developed fire and requested further resources to bring the fire under control.
“At its height more than 40 firefighters, seven fire engines and two height appliances were in attendance.
“There are no reported casualties and crews continue to work to extinguish the fire.”