Prentice Neal O'Steen was born on July 19, 1919 in Bedford County, TN to Susannah W. Reid and John Edward O'Steen. He grew up on a farm and attended high school at Forrest High in neighboring Marshall County. After graduation, O'Steen worked as a Bible salesman and traveled as far as Eastern Ohio. This endeavor proved unsuccessful, and O'Steen moved to Detroit to live with one of his brothers and work as a dishwasher in a restaurant. He later moved to Nashville to live with another brother and work in a meat packing plant.

O'Steen claims that he volunteered for the Navy in order to avoid the Army. He believed that he would inevitably be drafted and thought that the Navy would be a way to avoid the treacherous stories that he heard from World War I. O'Steen was stationed at Norfolk Naval Air Base for three months before aptitude tests dictated his placement in the Hospital Corps School in Portsmouth, Virginia. After completing this program, he worked in a military hospital taking blood pressure for a year. He was then assigned to San Francisco, where he worked as the pharmacist's mate on a tugboat that dragged targets for aircraft practice. O'Steen was recalled to service during the Korean War, when he worked at the Norfolk Naval Air Station.

After being discharged from the Navy, O'Steen served as a writer and an editor for newspapers in the Knoxville and Kingsport areas. He eventually became the editor of the Torchbearer at the University of Tennessee in Knoxville.