Chiat was born in the Bronx in 1931. He attended Rutgers University, graduating from its school of education in 1953. After a stint in the Air Force, he opened his own agency in Los Angeles in 1962. Six years later, he teamed with copywriter Guy Day to start the agency that bears his name. Under Chiat's leadership, Chiat/Day was named Advertising Age's "Agency of the Year" in both 1980 and 1988. In 1990, on the strength of breakthrough ads like the "1984" launch spot for the Apple Macintosh, the magazine named the shop "Agency of the Decade." In the mid-'90s, Chiat sold the agency to Omnicom and eventually left the agency business to found new media company Screaming Media. In 1999, he was listed among the top 100 advertising people of the century by Advertising Age and inducted into the American Advertising Federation's Advertising Hall of Fame.