Heavy smoke continued to billow from the business, located in a strip mall on Albion Road near Islington Avenue, well after crews first arrived on the scene at about 6 p.m.
The blaze was difficult to fight because it was in the basement, where rolls of fabric were stored, and the floor eventually collapsed, according to officials.
The fire was "pretty much knocked down" by mid-evening said Paul Richardson, acting platoon chief of Toronto Fire Service. "But we'll be here for a long time making sure the fire hasn't got into the walls and up into the other units."
There are no reported injuries. Crews evacuated the entire plaza, including the apartments located above. Officials believe 10 to 15 people were displaced by the fire.
It is unclear how the fire started.