After graduating from the Auburn University School of Architecture in 1978 and working fourteen years for two firms in Birmingham, Gary established his one-man firm Gary Justiss Architect in 1993.

To date, he has designed over a hundred custom homes, as well as numerous commercial, recreational, and civic buildings. He lives and works with his wife, three children, three dogs, and about 20 chickens in Chelsea, Alabama. The vast majority of his work is in new urbanist communities such as Seaside, Alys Beach, Rosemary Beach, WaterColor, Blount Springs, Mt Laurel, Lakeside and Hampstead. He has participated as an architectural consultant for numerous charrettes for Duany Plater-Zyberk & Company, Dover Kohl & Partners, The Architectural Charrette Team, The New Urban Guild, and the CNU. These include projects in Florida, Alabama, Tennessee, Mississippi, Georgia, Panama, Costa Rica, Ecuador and Mauritius.

Gary is an active member of the new urbanist and traditional architectural communities. He is a member of the Seaside Institute, The Institute of Classical Architecture, and a founding member of The New Urban Guild. He is registered to practice architecture in Alabama (#2402), Florida (#AR0015086), and Georgia ( #RA012695).