Leon Lebègue began his career in Paris, circa 1885, with Paul Colin, then inspector of Fine Arts. He began in the 1890s to pursue career as an illustrator for satirical newspapers: Sun Sunday, Laughter, La Plume, Le Gaulois, La Vie en Rose, the Latin Quarter, The Patriot Illustrated, Cycle, Modern Review, Grimace, Our Caricatures, The Illustrated National, Gil Blas Illustrated, The French Mail, and The Taste Parisien.

He designed many menus, programs, illustrated cards, book covers, bookplates and many book illustrations: Boitelle, The Substitute, The 25 francs from the top, The Mistress and Other new de Maupassant; Regrets Belle Heaulmière of François Villon; and works of Anatole France, Balzac, Théodore de Banvill, Huysman, Pierre Louys, and Musse. Lebègue is also known for having produced many posters, including that of Salon des Cent in 1895.