Holbrook started wrestling and running track when he was in middle school in Adrian, Michigan. He believes that the mental toughness served an important factor in fighting which he was well-trained in this department by his middle school wrestling coach Jim Waters. He started training MMA after he had his hands in a few fights. Besides training at IBG in Indiana, he also has trained at Tiger Muay Thai in Phuket Island, Thailand.
Holbrook fought in various regional MMA promotions, primarily in Indiana such as Absolute Cage Fighting, Midwest Fight Series, Colosseum Combat and Michiana Fight League prior to joining the UFC. He stepped in to replace an injured Joe Lile Jr. against Tyler Combs at the Colosseum Combat 32 lightweight title bout and won the fight via TKO and became Colosseum Combat lightweight champion.
He amassed a record of 11 undefeated wins, 10 stoppages with nine of them by submission, prior to signing with the Ultimate Fighting Championship. Holbrook made his promotional debut on short notice, as he was tabbed as an injury replacement for Erik Koch against Ramsey Nijem on July 25, 2015 at. Judges scored the bout 29-28, 28-29 and 29-28 in favor of Holbrook and won the fight via split decision. Holbrook was scheduled to face Sage Northcutt on January 30, 2016 at UFC on Fox 18. However, he was forced to pull out of the fight due to foot injury and was replaced by Bryan Barberena. Holbrook faced Joaquim Silva on July 8, 2016 at. Silva struck Holbrook with a punch after he caught his kick and followed by raining down a series of hammer fists, resulting in a knockout loss in round one. Holbrook next faced Jake Matthews on November 27, 2016 at. Holbrook won the fight via split decision with the scores of 29-28, 29-28 and 28-29. He said in his post fight interview “ felt good. I was expecting to be an underdog, going into somebody’s home town. It was kind of nice, and everybody enjoyed the fight I think." At UFC 210, Holbrook faced Gregor Gillespie on April 8, 2017. Gillespie threw a left hook and knocked out Holbrook 21 seconds into first round. Holbrook faced Thibault Gouti on September 2, 2017 at UFC Fight Night 115. He lost the fight via TKO in the first round. On June 21, 2019 it was reported Holbrook was released from UFC.
