During his early years, Tommy grew interested in sports, BMX bicycles, motorcycles, and soccer. He was shy around girls for quite some time until he noticed how girls were interested in bigger and "buffer" guys, so he took up bodybuilding. He entered a "hot body" contest in a local bar, and although he lost the contest, he met a man who offered him work as a stripper. For ten years Tommy worked as a male stripper, traveling all over the country and the world.
Beginning his career in pornographic films in 2004, Gunn was soon recognized as the 2005 AVN Best Male Newcomer award. He likewise received the 2006 AVN Best Supporting Actor for his role in Pirates and a second AVN Male Performer of the Year for 2007.
In 2007, Gunn appeared in the music video for "The Moneymaker" by American indie rock band Rilo Kiley. He also appeared in the music video "Too Drunk" by the band Buckcherry. In 2010 Gunn appeared in an episode of Entourage. In 2011 he had an unbilled role in Mommy & Me, a comedy film, directed by Jennifer James. In 2012 he appeared in the Louis Theroux documentary "Twilight of the porn stars" discussing the porn industry and his personal experiences within it. In 2014, he appeared in the horror film Wolves, directed by David Hayter.
In 2009, Gunn directed and starred in a 3-D choose-your-own-adventure movie titled Cummin' At You 3D.