He is the first Japanese-born chef to head up a top European restaurant in the UK, following a long career in France.
Sugimoto previously worked at Imperial Hotel in Tokyo before joining the two Michelin-starred Hôtel de Carantec in Brittany.
He then spent nine years at the three Michelin-starred Le Meurice in Paris, where he progressed to head chef under the guidance of Yannick Alléno and Alain Ducasse.
His new appointment comes six months after former Square chef-patron Philip Howard sold the business to Marlon Abela’s MARC restaurant group.
Sugimoto is reportedly planning to ‘modernise’ the Square by moving from a three to four-course menu featuring lighter dishes with less butter, according to Bloomberg.
Howard, who ran the Mayfair restaurant for 25 years, will launch his new restaurant, Elystan Street with long-term business partner Rebecca Mascarenhas in Chelsea later this month.
“The Square had become a bit of a struggle,” Howard told this month’s Restaurant Magazine. “I was cooking in a way that didn’t feel comfortable…the luxurious, relatively complex and detailed food no longer represented where my food soul lay.”
He added that while it was sad to say goodbye to the restaurant, ‘not a single cell in my body regrets the decision’.
Dishes at Elystan Street will be diverse and accessible, with a traditional roast offered on Sunday lunchtime.
However, Howard remains confident that the venture will be a success.
He said: “It will be super ambitious. I expect it to feature in all the guides, and right up near the top.”
The Square opened in 1991 and has held two Michelin stars since 1998.