Fire crews were called to Asda in Peterhead after a fire was discovered in the loft space.
Three appliances from the town were sent to the supermarket at 11.18am.
A fire spokeswoman said a fire was discovered in the loft space and staff evacuated the supermarket.
She said 13 crew members extinguished the fire and “isolated the electricity supply” in the area. A stop message came in at 11.35am.
The spokeswoman added that one appliance remains at the scene while they wait for a heating engineer to arrive.