At the age of 16, he lied about his age and enlisted in the United States Navy during World War II. Assigned to a Navy communications school in Los Angeles, he spent his free time at the Hollywood Canteen, talking to stars who dropped by to support the servicemen and women. A year after he enlisted, the Navy discovered his real age and discharged him.
Holliman returned home and finished high school. As soon as he was old enough, he re-enlisted in the Navy and was stationed in Norfolk, Virginia. Interested in acting, he was cast as the lead in several Norfolk Navy Theater productions.