Gary Barker Hansen was born in 1935 in Ogden, Utah to Clarence James Hansen and Lena Barker Hansen. When Hansen graduated from high school in 1953, he attended Utah State Agricultural College (now Utah State University), where he graduated with a BS in 1957 and received a commission as a second lieutenant in the United States Army Ordnance Corps. Lt. Hansen entered the U.S. Army in July 1957, serving at Aberdeen Proving Ground in Maryland and Tooele Army Ordnance Depot in Utah, and received an honorable discharge as a first lieutenant in June 1959.

From September 1959 to September 1961, Hansen was a missionary for The Church of Jesus Christ of Latter-day Saints in Great Britain. He served in the British, North British and Scottish-Irish Missions, helping set up the latter two missions and serving as mission secretary in both of them.

After two years in Great Britain, Hansen returned to Logan to attend Utah State University and work for Prof. Leonard J. Arrington. He married Helen Ure in September 1962 and soon received his MS degree in economics in June 1963. During that summer, he co-authored, The Richest Hole on Earth with Prof. Arrington, published as a research monograph by Utah State University. He continued his studies at Cornell University and spent a year as a Fulbright Scholar at the London School of Economics in 1965-1966. He completed his studies at Cornell, and, subsequently, received his PhD from Cornell in 1970. Hansen and his family returned to Logan in September 1967 to accept an appointment as an assistant professor of economics. During his 31 years at USU, he served as a professor of economics, and also as a professor of management and human resources. Hansen became a professor emeritus at USU in November 2000. Throughout his career Hansen published 110 books, chapters, articles, research reports and documents, and made over 150 professional presentations.

While teaching at Utah State University and after his retirement, Hansen worked extensively as a consultant to the U.S. Department of Labor and other state and national committees and task forces, plus the International Labor Organization and other international agencies. He was also a member of a number of professional organizations, including the American Economic Association, Industrial Relations Research Association, American Society for Training and Development, and the International Industrial Relations Association. In the 1980s he worked throughout the United States helping state and local governments implement programs to assist dislocated workers, plus giving testimony before Congress and other national commissions, and spending one year serving on the secretary of labor's Task Force on Worker Dislocation, a group whose report provided the framework for the passage of national legislation that was signed into law by President Ronald Reagan in 1988. During the 1990s, he served three years on the Federal Committee on Apprenticeship and worked in 11 countries in Southeast Asia and Central and Eastern Europe (Thailand, Nepal, China, India, Poland, Hungary, Bulgaria, Romania, Macedonia, Serbia and Ukraine) helping national and local community leaders learn how to organize and implement economic development and job creation programs.