Around half of the unoccupied Cragg Mill on Great Horton Road was said to be in flames after 7pm.
Local residents were advised to stay inside and close windows and doors.
West Yorkshire Fire and Rescue Service said: "Crews are currently dealing with a large unoccupied building fire in Great Horton area. 8 fire appliances are in attendance with supporting appliances and officers from across the brigade.
"The building is 50% involved in fire approx. 60m x 30m, 6 large jets, 4 breathing apparatus and positive pressure ventilation in use."