Chef Benoit Violier, whose Swiss restaurant was named the best in the world in December, has been found dead at his home.
Mr Violier, 44, ran the Restaurant de l'Hotel de Ville in Crissier, near the city of Lausanne.
It earned three Michelin stars and came top in France's La Liste ranking of the world's 1,000 best eateries.
Swiss police said Mr Violier, who was born in France, appeared to have shot himself.
The Swiss news website 24 Heures said (in French) that Mr Violier had been due to attend the launch of the new Michelin guide in Paris on Monday.
His death comes only months after that of Philippe Rochat, his mentor and predecessor at the Restaurant de l'Hotel de Ville, who fell ill while cycling.
Having worked at the restaurant since 1996, Mr Violier took it over along with his wife Brigitte in 2012, later obtaining Swiss nationality.
A keen hunter, he was known for signature dishes including game and produced a weighty book on game meat last year.
The restaurant's menus ranged from a quick lunch menu at 195 Swiss francs ($191; £134) to a "discovery" set menu priced at 380 Swiss francs.
According to a biography on his website, Mr Violier grew up in a family of seven children in the town of Saintes, in western France.
His passion for gastronomy was inspired by his mother from a young age, while he learned about wine, cognac and hunting from his father.
He moved to Paris in 1991, training with top French chefs including Joel Robuchon and Benoit Guichard.
He said his time there taught him "rigour, discipline and the art of the beautiful gesture".
In an indication of the standards he held himself to, he said: "Nothing is ever definitive, everything must be repeated every day."
Accepting the La Liste award, given by France's foreign ministry as an alternative to the World's 50 Best Restaurants prize, Mr Violier said it was an "exceptional" honour that would "only motivate our team more".
Swiss chef Fredy Girardet, who also received three Michelin stars, told 24 Heures that he was "dumbfounded" by news of Mr Violier's death.
"He was a brilliant man," he said. "Such talent, and an amazing capacity for work. He was so kind, with so many qualities. He gave the impression of being perfect."
French chef Pierre Gagnaire tweeted: "My thoughts go out to Benoit Violier's family. Very sad news about an extremely talented chef."
Paul Bocuse, another leading French chef, described Mr Violier as a "great man and a gigantic talent".
The Michelin Guide said he had "immense talent" and its thoughts were with Mr Violier's family and colleagues.