O'Connell turned his attention to mixed martial arts to supplement his Football training.
[6] O'Connell made his professional MMA debut in 2007 with no striking training other than cardio kickboxing which he would do to help stay in shape.
Despite having limited training, O'Connell was successful early on in his career and held an overall record of 6–2, which earned him an invitation to compete on The Ultimate Fighter: Team Nogueira vs.
[4] O'Connell was the co-host of a popular sports talk radio show on ESPN700 in Utah called The OC and Hackett Show[7] O'Connell made his promotional debut as a short notice injury replacement at The Ultimate Fighter Nations Finale on April 16, 2014, against Ryan Jimmo.
[12] On January 18, 2015, O'Connell then faced Matt Van Buren at UFC Fight Night 59.
Goofs include booping Matt Van Buren on the nose or playing an improvised game of rock-paper-scissors with Perosh.
In his debut, he faced Ronny Markes at PFL 2 on June 21, 2018, in Chicago, Illinois, winning the fight by TKO in the second round.
He won the back-and-forth fight via TKO between the third and fourth round after Vinny Magalhães stopped the bout.
With the win, O'Connell was crowned the 2018 PFL Light Heavyweight champion and earned the $1 million cash prize.
Of note O’Connell worked as a broadcaster for the PFL commentating cage-side once on the same night as one of his own fights.