Career
Hartt made his professional mixed martial arts debut on December 11, 2004, when he faced Gary Bonenfant at Mass Destruction 18. Ultimate Fighting Championship
With an undefeated 5–0 record, Hartt signed with the UFC in June of 2008. Hartt made his debut against fellow newcomer Shannon Gugerty at UFC Fight Night: Silva versus
Irvin on July 19, 2008.
He lost the fight via rear-naked choke. In his second fight with the promotion, Hartt faced Corey Hill at UFC: Fight for the Troops on December 10, 2008.
Hartt then faced Dennis Siver at UFC 99 on June 13, 2009. He lost the fight via rear-naked choke, and after dropping to 1–2 in the UFC, was released from the promotion.
Post-UFC career
In his first fight after being released from UFC, Hartt faced Guillaume DeLorenzi at Ringside Mobile Marketing Association : Number Escape on June 18, 2010.
He lost the fight via shoulder injury TKO.
