Hallman earned his bachelor of science in economics at the College of Charleston in 1982 and a master's in business administration at the University of South Carolina in 1985. He began his career as a manager for PGA tour golfers, starting as a marketing consultant for Corey Pavin. Soon tiring of the constant travel, he began looking for an opportunity for a more stable position.
Hallman moved to Birmingham in 1992 to manage the inaugural Bruno's Memorial Classic golf tournament. He founded the Bruno Event Team with Ronnie Bruno in 1995 which specializes in managing operations at large sporting events. In addition to golf tournaments, the company and its subsidiaries have managed races at the Barber Motorsports Park, national soccer team friendlies and World Cup qualifiers at Legion Field, the 009 Davis Cup first round tie tie at the BJCC, title bouts for heavyweight boxer Deontay Wilder, the Southeastern Conference Baseball Tournament at the Hoover Metropolitan Stadium, and football game-day operations for the Magic City Classic, the Alabama Crimson Tide and the Tennessee Volunteers. The Bruno Event Team now has offices in twelve cities.
Throughout his career, Hallman has been one of the most prominent voices in favor of building a domed stadium in Birmingham. In December 2017 he was named "CEO of the Year" for companies with 25-50 employees by the Birmingham Business Journal. He was also recognized as the 9th "Most Influential" sports figure in Alabama by the Birmingham News, and he and the Bruno Event Team were named "Tourism Promoter of the Year" by the Alabama Restaurant & Hospitality Association.
- "Client Spotlight: Gene Hallman" (June 8, 2015) Sirote & Permutt/al.com
- Steere, Tim (May 6, 2016) "Hallman knows the score." Birmingham Business Journal
- Johnson, Roy S. (July 15, 2016) "As Birmingham evolves as a sports town beyond football, will city finally get a dome? An NFL team?." The Birmingham News
- "Ranking the top 25 most influential people in Alabama sports." (August 2, 2017) The Birmingham News
- Rebman, Stephanie (December 8, 2017) "Winners unveiled in BBJ's 2017 CEO Awards." Birmingham Business Journal