Sodexo already provide public catering at the show’s Charity Gala Preview, and hospitality at RHS Hampton Court Flower Show, as well as at events such as Royal Ascot, Henley Royal Regatta and The Open.
The RHS's contract with Fortnum and Mason's has ended and they will no longer provide corporate hospitality at Chelsea.
In 1984, Blanc opened Belmond Le Manoir aux Quat’Saisons in Oxfordshire, which has retained two Michelin stars for over three decades.
Under the new partnership, Sodexo Prestige and Raymond Blanc will serve a variety of packages and experiences including breakfasts, champagne receptions, lunches, afternoon teas and evening private dinners.
Blanc said: "The RHS is a standard bearer of excellence in horticulture, while the RHS Chelsea Flower Show is arguably the most extraordinary gardening event in England... and possibly the world no less. As for me, I’ve always been in love with gardens. From them, the colourful plants will flourish and the heritage vegetables will grow. From the garden, my gastronomy is born. Each season will bear its drama and its own beauty. In partnership with the RHS and Sodexo Prestige, I truly look forward to designing a space, menu and experience that will delight our guests."
Alex Beaumont, events director at Sodexo Prestige said: "For me, the Royal Horticultural Society is one of my best clients and along with my team we always give our very best to deliver a successful show for the RHS and their customers. This opportunity allows us to do something very different at RHS Chelsea Flower Show.
"Working with Raymond Blanc we see huge opportunity to grow and develop our teams of both chefs and front of house staff with the help and guidance of such an inspirational figurehead. We are hugely excited and look forward to a long and fruitful relationship with the Raymond Blanc team."
Clare Hinde, head of special events at RHS, said: "Our world class RHS Chelsea Flower Show deserves to offer nothing but world class dining so I am absolutely thrilled that our hospitality guests will get nothing but the best. The partnership of the RHS, Sodexo Prestige and Raymond Blanc is very exciting and I cannot wait to see what delights Raymond and the team will thrill us with."