Born Kemal Amen Kasem, Casey Kasem grew up in a Lebanese-American household in Detroit, Michigan. He made his radio debut while in high school and studied radio broadcasting while a student at Wayne State University. He became involved in radio acting with roles on shows like The Lone Ranger. In 1952 he was drafted into the U.S. Army where he was a successful announcer and dj for the Armed Forces Radio Korea Network.

After returning from Korea, Casey Kasem spent most of the next two decades working his way up to national prominence as a radio announcer. In 1970, working with childhood friend and Hollywood producer Don Bustany, Kasem proposed a countdown radio show loosely based on the 1940's and 1950's hit show Your Hit Parade. The result was American Top 40 which debuted on July 4, 1970 on 7 radio sations.

American Top 40 quickly became one of the most popular syndicated radio shows in the country and then around the world. By 1986 the show was featured on more than 1,000 radio stations in 50 countries around the world as well as Armed Forces Radio and the Voice of America.
American Top 40 spawned a television spin-off, America's Top 10, that ran from 1980 through 1990 and featured Casey Kasem counting down the week's top 10 hits and playing music videos.