The blaze at the Edrington Group's site in Glasgow in June 2011 happened when whisky hit a light fitting as casks were being filled.
An investigation by the Health and Safety Executive (HSE) found that the lights should not have been used in a flammable atmosphere.
The company was fined £40,000 at Glasgow Sheriff Court after admitting breaking health and safety laws.
Two workers were on a metal walkway at the top levels of the warehouse, on Great Western Road, using flexible hoses to fill 450-litre casks with whisky pumped from steel vats, the court heard.
One of them said he felt the hose relax before a jet of whisky shot up towards a light fitting above a forklift truck. It hit the light fitting and flames engulfed the cage of the forklift truck.
Both men ran towards the stairs at the back of the warehouse, setting off the fire alarm as they left, prompting the evacuation of the site.
HSE inspectors said the two workers were "extremely lucky" not to have been killed or seriously injured.
Their investigation found that the central aisle lights in the warehouse should not have been used and had they been checked, they would have been identified as an ignition-source risk.
After sentencing, HSE inspector David Stephen said: "This was a major incident. The two workers were extremely lucky not to have been killed or seriously injured.
"More than 17,500 litres of whisky were lost."
A Edrington spokesman said: "The company took full responsibility for this incident from the outset.
"Edrington takes the health and safety of its employees extremely seriously."