Grellet was born October 9, 1869 in Tours. He was a student at the Beaux-arts de Paris from 1890, and began to produce drawings for the press, titles such as Paris-Joyeux (1894), Le Journal pour tous , La Caricature (1895-1902), Gil Blas illustrated , Fin century , Le Rire , La Vie pour rire (1900), The Comic Family Album (1903), L’Indiscret , Le Sourire (1917-1921), Ridendo (1934-1940), Scaramouche (1936). He signed some of his compositions “Géogrell” and was a member of the Humorists. He married in 1905 a young artist, Hortense Vuischard.
During the First World War, he made many drawings of the front. Grellet produced lithographed advertising posters such as À la Place Clichy and Au Bon Marché (1900). He designed the character of “Doctor Valda” for the lozenges of the same name. In the 1920s, he collaborated on the albums of the company “L’Estampe moderne” directed by Octave Bernard.