Mahoney's ancestry is a unique blend of French, Irish, and Cherokee heritage. His athletic prowess was evident during his time at the University of Iowa, where he excelled in swimming, basketball, and football.
When World War II erupted, Mahoney enlisted in the Marines, serving as a fighter pilot and instructor. After the war, he transitioned to a career in Hollywood, becoming a renowned stuntman. He had the distinction of doubling for legendary actors such as Errol Flynn, John Wayne, and Gregory Peck.
Mahoney's talents caught the attention of Gene Autry, who cast him as the lead in the 1951 TV series "The Range Rider," a show that ran for 78 episodes. He also tested for the role of Tarzan, but ultimately lost out to Lex Barker. However, he did appear in Gordon Scott's "Tarzan the Magnificent" (1960),playing the heavy and performing all his own stunts.
Mahoney's health began to deteriorate, and he contracted dysentery, dengue fever, and pneumonia while filming "Tarzan's Three Challenges" (1963). Despite his illnesses, he continued to work on the set. However, his contract with Sy Weintraub was eventually dissolved due to Weintraub's desire to cast a younger Tarzan in a potential TV series.
After a couple of years to regain his strength and weight, Mahoney returned to the action film genre, marking the beginning of a new chapter in his career.