They are now are dampening down at the site while an investigation gets underway to assess the extent of the damage.
The incident happened in a unit on Faraday Road on Southfield Industrial Estate late last night.
Two buildings are believed to have been badly damaged.
A spokeswoman said: “The Scottish Fire and Rescue Service was alerted at 11.15pm on Monday to a fire within industrial units in Glenrothes.
“Operations Control immediately mobilised a number of fire engines to Southfield Industrial Estate, Faraday Street where firefighters extinguished a large fire.
“There were no casualties.
“Firefighters are still dampening down the affected area and will remain on scene for some considerable time.’’
Around 40 firefighters were called to the scene last night.
The two buildings were well alight when they arrived.
There are no reports of any injuries, but roads within the area may be closed while investigations continue.