Zumbrunnen plans to pursue new career paths after ten years in the general management of MGB and five years as its president.
MGB noted that the process of searching for a successor is underway and Zumbrunnen has assured the administration that he would be available for a smooth transition.
Zumbrunnen commented, "After more than 26 years at Migros, I have decided to start something new. The last ten years in general management, five of them as its president, were demanding but also exciting.
"It has been an honour and a pleasure for me to work with many colleagues to further develop Migros Group in its many dimensions so that it is ready for the challenges ahead. On the one hand, it is difficult for me to leave this great company with its committed employees. On the other hand, I am looking forward to the tasks ahead."
Zumbrunnen was instrumental in streamlining the company's corporate portfolio, expanding Migros Group's position in Swiss online retailing, and pushing ahead with the establishment and expansion of its health business.
During his tenure, Migros Industrie launched innovative new products, such as the plant-based range under its own brand V-Love or CoffeeB.
He has also led Migros Bank, Medbase, and Hotelplan as chairman of the board of directors.
Under his leadership, the company has pledged to achieve net-zero emissions by 2050, in line with the Paris Climate Agreement.
Migros president Ursula Nold thanked Zumbrunnen for his service on behalf of the administration of MGB and added, "I very much regret Fabrice Zumbrunnen's decision.
"He has brought Migros Group forward with his distinctive analytical skills, his very sound contextual knowledge, but also with his consensus-oriented manner."