Fire crews were called to the scene at Nick’s on Henderson Street at 8.17pm on Saturday and found a “well developed” fire in the kitchen.
Pictures on social media showed smoke and flames pouring from the building.
Nairn said that no one was hurt as a result as he praised emergency services.
Hr said in a tweet: “Just to let you know, terrible fire at Nicks BofA tonight, but thankfully all staff and customers unhurt.
“Huge respect and thanks to the emergency services who were incredible.”
Nairn said that the fire happened “right in the middle of service" and was a result of a piece of kitchen equipment malfunctioning.
It is understood that the fire was caused by an exploding deep-fat fryer.
The star chef said the fire took hold within 90 seconds with the equipment ‘exploding’ after staff ran out of CO2 extinguishers to treat the fire.
He said: “Luckily an off-duty cop and off-duty firefighter were dining with us.
"They assisted with the evacuation.
“It’s scary how quickly it happened. It wasn’t an accident, it was an electrical fire.
"We threw a fire blanket over it and discharged two CO2 extinguishers. But as soon as they ran out, it exploded.
“We’re all standing outside, there’s just devastation.”
Nairn added that the devastation of the fire was a cruel blow after the impact the pandemic has had on business.
He said: “It’s a bitter pill to swallow after the last 18 months. We have to ask ourselves what’s next, we’ve already been flooded.”
The Fire Service confirmed that a “well developed fire” had occurred in the kitchen of the Bridge of Allan restaurant.
Six fire engines and a command support unit were sent to the scene.
Police also attended.
Two people were treated for smoke inhalation.
A Scottish Fire and Rescue Service spokesman said: “We got a call at 8.17pm to a building alight. We sent two crews from Dunblane and Tillicoultry.
“On arrival crews confirmed this was a well developed fire within the kitchen and requested further attendance.”
Further appliances and a command support unit were then sent to the scene.
Nairn further tweeted that he was still processing the “enormity” of the fire at the Bridge of Allan restaurant.
However, he added that he was “overwhelmed by the love” people have shown him as a result of the devastating blaze.
He added: “Thank you all so much. Love right back at you.”
Nick’s on Henderson Street thanked people for their support in a Facebook post, which said: “After an eventful evening, we want to let you all know every staff member and customer are safe and well and we want to thank the extraordinary amount of support and love we’ve felt from so many people- it’s so appreciated! We’ll be back, we promise.”
Brought up in Callander, Nairn, 62, is one of Scotland's best known celebrity chefs.
He opened his first restaurant, Braeval, near Aberfoyle in 1986 before being awarded a Michelin star five years later.
Nairn is the youngest Scottish chef to win a Michelin star.