Joe Giella attended the School of Industrial Art and the Art Students League in New York City, and took commercial art courses at Hunter College. Giella's education was interrupted for eight years while he served in the Navy Reserve. Giella worked as a comic book artist for the medium's two major publishers, DC and Marvel.
In addition to his work on superheroes, Giella did freelance work for such prestigious firms as McCann Erickson, Saatchi & Saatchi, Doubleday and Communigraphics. Giella's work for publisher Simon & Schuster includes a strength and fitness book and a superhero cookbook. He has worked on many syndicated comic strips. Giella penciled and inked 'Batman' for four years (1966), doing his best to imitate Bob Kane. Joe Giella assisted on several syndicated strips, including 'Flash Gordon', 'The Phantom', 'Johnny Reb' and 'Sherlock Holmes'.
In 1991, Joe Giella started drawing 'Mary Worth' for King Features. It is one of the classic soap-opera comic strips, which was scripted by John Saunders until 2003 and by Karen Moy since then. In 2006, the United States Postal Service honored Giella by using his art on two postage stamps in the DC Comics Super Heroes Collection. Joe Giella retired from the 'Mary Worth' comic in August 2016, at the age of 88.