LEON was founded on the twin principles that food can both taste good and do you good.

When Henry Dimbleby, John Vincent and Allegra McEvedy opened their first restaurant, on London's Carnaby Street in July 2004, their aim was to change the face of fast food. Six months after opening, LEON was named the Best New Restaurant in Great Britain at the Observer Food Monthly Awards (by a judging panel that included Rick Stein, Gordon Ramsay, Nigel Slater, Heston Blumenthal, Ruth Rogers and Jay Rayner). In 2015, Henry Dimbleby and John Vincent received MBEs for their work improving the quality of school lunches. There are now more than 70 LEON restaurants.

LEON has published more than 20 cookbooks including LEON Fast Vegan, LEON Happy Salads, LEON Happy Baking and LEON Happy Fast Food.