The blaze broke out at about 01:00 BST at the premises on Canonbury Street in Berkeley.
Four fire engines were called out to the two-storey building that was empty at the time. No-one was hurt.
A number of people living nearby reported hearing a loud "pop" and were woken by the smell of smoke. The cause of the blaze has not been confirmed.
A commercial property in Gloucestershire has partially collapsed after a fire overnight.