Gary Mullen embarked on his pro career by signing with the Detroit Lions as a free agent in 1985 where he was a training camp cut. He signed in 1986 with the Pittsburgh Steelers but left training camp due to illness. He accepted a tryout invite from the new Arena Football League's Denver Dynamite and ended up leading the team with 26 receptions for 502 yards and 11 touchdowns in 6 games to help the team win the first ever Arena Bowl as the game's MVP. His performance led Mullen to the NFL as a replacement player for the NFL's Chicago Bears. Mullen caught 2 passes for 33 yards for the "Spare Bears". The Dynamite suspended operations and their players became property of a new Arena franchise, the Los Angeles Cobras. The Cobras folded after one season and Mullen initially sat out 1989 rather than take a pay cut. He returned to field late in the season with the Detroit Drive. Mullen spent four seasons in the Motor City, helping the Drive win titles in 1989, 1990 and 1992. Mullen was traded by the Drive after the 1992 season to the Cincinnati Rockers for future considerations. After one season in Cincinnati, he was selected by the Milwaukee Mustangs in an expansion draft (the Rockers also folded) and spent his final season there in 1994. In his 8-year Arena career, Mullen caught 254 passes for 4,021 yards and 73 majors. He was first team All-Arena three times and second team once. Mullen was inducted into the Arena Football Hall of Fame in 1998.
Mullen wore this Wilson porthole mesh jersey in 1988 for the Cobras in their only season of existence and paced the team with 61 catches for 823 yards and 17 scores. It shows light game wear consisting of a small number of impact marks. It has the Arena Football patch over the right collarbone. The jersey is typical of other early Arena game worn jerseys in that is was made short and the name has been screened directly on the jersey without the use of a nameplate. Mullen signed the left shoulder in silver Sharpie.