The chef - and co-presenter Kate Humble - will transform a section of the famous site for a new four-part TV show called Kew On A Plate.
The BBC2 show will explore the history of fruit and vegetables in the UK and Blanc will offer tips on how home cooks can make the best of them.
He said: "What a privilege it is to be working on this project. I am sure viewers will share my inspiration and passion for British heritage, the garden and the glorious food I will cook from it."
The Royal Botanic Gardens at Kew, London, were founded in 1759 and declared a Unesco World Heritage Site in 2003.
It is home to thousands of rare species of plants.
Humble said: "There is astonishing history, science and stories of human endeavour behind the everyday vegetables we grow, cook and eat."