The blaze was discovered at Shortridges Laundry on the Irongray Industrial Estate shortly before 4 am. It had broken out in a number of laundry cages in the yard.
Fire crews tackled the flames and it was eventually extinguished but the laundry units and cages were damaged as was part of the fabric of the actual building.
Sergeant Amy Ritchie at Dumfries said: “We are currently carrying out enquiries into the cause of this serious fire and a joint investigation will take place between the Fire and Rescue Service and Police Scotland.
“We want to hear from anyone who may have been in the Irongray Industrial Estate through the night if they saw or heard anything suspicious. No-one was injured in this incident, however the damage is extensive.”
Anyone with any information is asked to call officers at Dumfries on 101.
