Born at Barcelona, Gallardo studied in Spain, working for several Spanish advertising agencies, before moving to Munich, Germany in 1959. The next four years he spent working for the Delpire Agency in Paris, before travelling to the United States in 1963. Here he met Frank and Jeff Lavaty, who represent his work to this day.
In 1969, he was commissioned by Ballantine Books to create cover art for their Ballantine Adult Fantasy series. He went on to be the most prolific of their cover artists, creating a total of twenty-nine. Since then, he has created at least eighteen covers for other authors, including producing all of the artwork for his own release: The Fantastic World of Gervasio Gallardo. Eventually Gallardo returned to Barcelona to set up a studio. In 1977, 1978 and 1979 Gervasio Gallardo was represented at the International Art Fair of Basel by Sala Gaudí art gallery, where he exhibited individually in 1976 and 1978 and which today has a large part of his work.
Gallardo has won numerous awards within Europe and the United States, and has exhibited his work in Paris, Barcelona, and the United States.