He graduated from Huntington Beach High School in 1988 and attended the University of California, Riverside, where he earned a bachelor's degree in political science. It was at UCR that he started drawing editorial cartoons for his school paper, The Highlander.
In 1991, Steve won the Scripps Howard Charles M. Schulz Award as the top college cartoonist and the John Locher award for Outstanding College Editorial Cartoonist. He was influenced by cartoonists such as Jeff MacNelly, Paul Conrad, Pat Oliphant and Don Wright.
Breen was about to become a high school history teacher when the Asbury Park Press offered him a job in the art department in July 1994. He became the full-time editorial cartoonist there in 1996.
In July 2001, he returned to his home state to join the staff of The San Diego Union-Tribune. His editorial cartoons are nationally syndicated by Creators Syndicate, who acquired former syndicate Copley News Service in 2008. They regularly appear in The New York Times, USA Today, Newsweek and US News and World Report. His comic strip Grand Avenue appears in more than 150 newspapers across the country, syndicated by United Features Syndicate.
He is the author and illustrator of two children's books: "Stick" and "Violet the Pilot."