Levitz was born in Brooklyn, New York, to Hannah and Alfred Levitz. He attended Stuyvesant High School during which time he co-wrote and published a comic fan magazine, The Comic Reader, which according to Levitz, was the first regularly-published comics industry news fanzine. (The Comic Reader went on to win two Best Fanzine Comic Art Fan Awards.) One of Levitz's teachers, the future Pulitzer Prize winner Frank McCourt, was impressed enough with Levitz's work that he arranged for Levitz to appear on McCourt's brother's radio show. During the course of his research for the fanzine, he became well known at the offices of DC Comics, where in December 1972, editor Joe Orlando gave him his first freelance work, initially writing text pages and letter pages, and later working as a per diem assistant editor before writing stories. Levitz later studied business at New York University but took had no formal education in writing, other than a journalism course. He dropped out after three years in order to concentrate on his writing career.

DC Comics

After serving as Joe Orlando's assistant editor, in 1976 Levitz "fulfilled a lifelong dream" by becoming the editor of Adventure Comics on the eve of his 20th birthday. He also notably served as editor for the Batman line of comics. As a writer, Levitz is best-known for his work on the title The Legion of Super-Heroes, which he wrote off and on from 1974 until 1989. Of particular note are his collaborations with artists Michael Netzer , James Sherman, and Keith Giffen. He also wrote the Justice Society series in All Star Comics during the late 70's after Gerry Conway left the book. He was the co-creator of the Earth-2 Huntress with artist Joe Staton and of Lucien the Librarian with artist Nestor Redondo.

Levitz eventually became an editor, and served as vice president and executive vice president, before assuming the role of President in 2002.

In 2006, Levitz returned to writing the Justice Society with issue #82 of JSA, completing that volume before writer Geoff Johns' relaunch.

On September 9, 2009, it was announced that Levitz would step down as President and Publisher of DC Comics to serve as the Contributing Editor and Overall Consultant for the newly-formed DC Entertainment, and become the writer of both Adventure Comics vol. 2 and Legion of Super-Heroes vol. 6.

Comics he has written include:

• Legion of Super-Heroes vol. 2 #281-313 (DC Comics, November 1981 - July 1984)
• Tales of the Legion of Super-Heroes #314-325, 343 (DC Comics, August 1984 - July 1985, January 1987)
• Legion of Super-Heroes vol. 3 #1-63 (with co-author and artist Keith Giffen, DC Comics, August 1984 - August 1989)
• Legion of Super-Heroes vol. 4 #100, back-up story "The Fires of Creation" (with artist Walt Simonson, DC Comics, January 1998)
• Legion of Super-Heroes vol. 6 #1-present (with Y?ld?ray Ç?nar, DC Comics, May 2010)
• Adventure Comics vol. 2 #12-present (DC Comics, June 2010)
• Superman/Batman Annual vol. 1 #4 (DC Comics, June 2010)