Emergency services were called to Gallowfields Trading Estate in Richmond at about 3pm on Sunday.
Two crews from Richmond and Colborn attended the fire, which officers said had started inside an electricity supply room.
Fire and smoke damage was caused to the fuse board and cabling.
A spokesperson for North Yorkshire Police said a large cannabis grow had been discovered in a building on the site.
Officers attending the scene discovered more than 200 adult plants and a further 100 smaller plants, along with electrical and hydroponics equipment.
Nikki Chandler, who owns The Raw Store, which is based on the estate and supplies raw pet food, says the expansion of her business will be delayed as a result of the fire.