Smith has won the honour of cooking the main course dish at the final banquet for the television show. Nick Nairn was the only other Scots chef to win a dish through to the final banquet, in 2006.
The Inverness-born chef trained at Le Gavroche in London and worked with the Conran Group of restaurants before taking over the Three Chimneys kitchen in 2005 from founding chef Shirley Spear.
His winning main course dish, which will be served at the Comic Relief 25th birthday celebration dinner at the Royal Albert Hall, was called "I Love Kids, But I Couldn't Eat a Whole One".
It is a North African goat dish inspired by Comic Relief's work in Africa, with fried plantain fritters and tomato couscous.
Smith said: "To be the first Scottish chef to win in seven years is the thing I'm most pleased about."