Joël Robuchon, a master chef who shook up the stuffy world of French haute cuisine by emphasizing the delights of the simple mashed potato and giving diners a peek at the kitchen, died Aug. 6 in Geneva. He was 73. 

A spokeswoman confirmed his death. French media sources reported that he had cancer.

Mr. Robuchon’s career was one of superlatives: He was named among the best craftsmen in France in 1976, crowned cook of the century in 1990, chosen to be one of the chefs at the “dinner of the century” and for years held the most Michelin stars in the world.

He was known for his constant innovation and even playfulness in the kitchen — a revelation to the hidebound world of French cuisine. He built an empire of gourmet restaurants across the world, from Paris to such cities as Tokyo, Las Vegas and New York.

“To describe Joël Robuchon as a cook is a bit like calling Pablo Picasso a painter, Luciano Pavarotti a singer, Frederic Chopin a pianist,” Patricia Wells, a cook and food writer, wrote in “L’Atelier de Joël Robuchon,” a book about the chef and his students. “Joël Robuchon will undoubtedly go down as the artist who most influenced the 20th-century world of cuisine.”

While Mr. Robuchon was no stranger to the fancy — truffles and caviar were among his favorite foods — his cuisine was often described as simple because he preached the use of only three or four ingredients in most dishes. His goal was always to show off, not mask, their flavors.

He started a revolution with his “Atelier” (workshop in French) business model: small, intimate restaurants where diners sat at a counter surrounding the kitchen. They didn’t take reservations, and many didn’t even have tables.

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His goal, he said, was to make diners feel comfortable, let them interact with the chef and, above all, put the focus back on the food. It was partially a rebuke to the Michelin-star regime, which awards points not just for technique but also for ambiance and service.

But Michelin, and just about everyone else, gobbled up his culinary innovations. With Ateliers around the world, Mr. Robuchon reached a total of 32 Michelin stars in 2016 — a record — and still held 31 stars this year, including five three-star restaurants.

Joël Robuchon was born April 7, 1945, in the French town of Poitiers, south of the Loire Valley. He considered becoming a priest, but hours spent cooking with the nuns convinced him that he had another calling. He got his professional start at 15 at a local restaurant and by 29 was running the kitchen at a large Paris hotel, in charge of 90 chefs.

For years, his culinary home was at Jamin, a restaurant near the Eiffel Tower that he opened in 1981. The restaurant racked up a Michelin star a year in its first three years — a feat no one had accomplished before. The wait for a reservation was two months, even though the price for a meal without wine was $200.

Even at this classic restaurant, Mr. Robuchon shook up the culinary scene: His most famous dish was the lowly mashed potato.

“I owe everything to these mashed potatoes,” he said once during a demonstration of how to make the almost liquid dish. “Maybe it’s a little bit of nostalgia, Proust’s madeleines. Everyone has in his memory the mashed potatoes of his mother, the mashed potatoes of his grandmother.”

The idea that a restaurant might be a warm, casual place, rather than a stuffy temple to awkward food, was taking root. It was, in part, a rejection of “nouvelle cuisine,” the movement that made French chefs notorious for small plates, exquisitely presented but often not all that satisfying.

Mr. Robuchon hung up his whisk in 1996, retiring from day-to-day cooking at the age of 51.

“You have to know when it’s time to quit,” the chef told the Associated Press at the time. “A great chef has to be in great shape. Cooking is tough. It’s like being an athlete who has to stay really fit.”

He continued to consult with other chefs, work on a line of prepared foods and oversee restaurants across the world, but he declared that he was done with slaving away all day at the stove.

However, in 2003, Mr. Robuchon came out of retirement to create the Atelier, first in Paris and Tokyo and later in cities all over Asia, Europe and the United States.

His latest project came this year in Paris, with the opening in April of Dassai, a restaurant and tea-and-cakes salon with a bar for tasting sake, the rice-based alcohol of Japan.

Mr. Robuchon was married and had several children, but a complete list of survivors was not immediately available.