Born in St. Louis, Miller graduated from Washington University before commencing his career in radio. When a singer named Marvin Miller debuted on another St. Louis radio station, he began using his middle initial to distinguish himself from the newcomer. For the Mutual Broadcasting System, he narrated a daily 15-minute radio show entitled "The Story Behind the Story", which offered historical vignettes. He also served as announcer on several Old Time Radio shows of the 1940s and 1950s, including "The Jo Stafford Show" and the long-running mystery series "The Whistler".