Gabriel H. Mahon Jr. was born in Williamston, South Carolina, and later moved to Greenville, where he graduated from high school and briefly attended The Citadel. He began his career as a clerk in his father's retail store and later transitioned to a traveling salesman before founding his own retail business. Mahon served in both the National Guard and the U.S. Army during World War I, where he was decorated for his service. Post-war, he became active in the American Legion and held leadership roles within the organization. Additionally, Mahon served as a trustee for Greenville Woman's College and represented South Carolina in Congress from 1936 to 1939.

Gabriel H. Mahon Jr.'s political identity is marked by a blend of military valor and local governance, underscored by his dedication to veterans' affairs and education. His military accolades and leadership in the American Legion suggest a deeply rooted commitment to service, while his tenure as a trustee for Greenville Woman's College indicates a nuanced approach to educational advancement. Mahon's unexpected political career trajectory, from local business owner to national representative, hints at an ideologically flexible yet locally anchored political philosophy.