Rochat, 61, died at around 9.30am while cycling with two other people on the outskirts of Chesaux-sur-Lausanne, Le Matin newspaper reported online.
“The investigation is under way but it appears that he had a malaise,” Jean-Christophe Sauterel, spokesman for Vaud cantonal police told the daily.
Rochat succeeded renowned Swiss chef Frédy Girardet as head of the Hôtel de Ville restaurant in Crissier, near Lausanne, rated with three stars by the Michelin Guide.
He handed the reins over to chef Benoît Viloier while continuing to run a culinary consulting business, catering company and on-line boutique.
Rochat's skills as a cook were recognized in France, where in 2006 he was awarded the title of Chevalier in the national order of merit.
In 2013, he received an honorary doctorate from the University of Tours for his contribution to French gastronomy.
Born in the Joux valley in the canton of Vaud, Rochat was a passionate sportsman, 20 Minutes newspaper reported.
The chef was often seen pedalling his racing bike.
He married marathon runner Franziska Rochat-Moser, who died in an avalanche while ski touring in the Vaud Alps in 2002.