Stein was reportedly celebrating his 70th birthday elsewhere when the Porthleven property caught fire in the early hours of the morning.
Firefighters were called when smoke was seen escaping from the front door shortly after 1am. Fearing a huge explosion due to the presence of cylinders, they responded "aggressively" and managed to prevent it from spreading.
The scale of the damage and the cause of the blaze is still being assessed by experts but arson has not been ruled out.
Katherine Billing, the incident commander for Cornwall Fire and Rescue Service, confirmed that all possible causes were being considered.
"Whether it was arson or not is something that is still being investigated," she said.
"Because of the severity of fire damage, it is difficult to say at the moment."
Ms Billing added: "We were a maximum 15 mins away from the fire destroying the whole of the main restaurant.
"This would have meant a prominent business owner losing the opportunity to trade over the summer and would have spoilt the beauty of Porthleven and affected the economy of the whole village for the summer season."
She said a bin store where the blaze had apparently started had been so severely damaged it had been rendered "a shell" but the damage to the adjacent main restaurant was "minimal" and the business should be able to reopen within weeks.
Helston Fire, one of the two local fire crews that attended, said they had "worked very hard to stop spread of fire to restaurant".
Staff at Rick Stein Porthleven were unavailable to comment, but in a tweet the restaurant said it was just thankful no one was hurt.
Stein spent a large part of his fortune on a string of fish and chip shops and restaurants in the Padstow. The success of the empire in the town led to it being nicknamed "Padstein".
Three years ago, the celebrity chef expanded further by taking over an existing restaurant in historic Porthleven on the south coast - the scene of the fire.
Despite regularly promoting Cornwall on his many television appearances and shows, Stein has struggled to win over the local community.
In one row centred around his plans for a new accommodation block next to one of his hotels, Stein wrote to a hotelier accusing him of failing to appreciate the "rosy glow of publicity" his celebrity status has brought to the resort.
In the letter, he attacked those protesting at his plans and demanded "recognition" for his contribution to the area.
He implied that his fame has benefited fellow businessmen and even extended the holiday season.
Stein, who spends a lot of time at his Sydney home, is understood to have spent Sunday night with friends and family to belatedly celebrate his birthday, which was back in January.
This article was originally published by The Telegraph.
