Born in Arequipa, Guillermo Osorio started out working as an artist for La Prensa. In the 1960s, he became known as a cartoonist for El Comercio. One of his most famous works was 'Historia de un Candidato', satirical work about Peruvian politician Haya de la Torre. He also worked on the section 'Ají Molido' in Caretas. He cooperated with the magazine La Olla, for which he made the political satire 'Los Hermanos Picapiedra'.