McKenzie was born in Cordova, Alaska and currently trains in Spokane, Washington. He saw his first MMA fight when he was a sophomore at Selkirk High School and knew from then on that he wanted to be an MMA fighter.
McKenzie is a member of the "Fancy Pants Fight Team", named after Lyle Beerbohm. Prior to joining the Ultimate Fighting Championship, McKenzie recorded ten successive submission victories, nine of which were by guillotine choke.
McKenzie also utilizes his own variation of the guillotine choke which he names "The McKenzietine". McKenzie flips his shoulder a different way to the standard guillotine choke, before arching his shoulder. According to Sherdog.com, McKenzie has the third-most guillotine choke victories in the world behind only two fighters who have each had over 50 fights in their respective careers, one being Travis Fulton, the front-runner, who despite having had over 300 fights has only two more guillotine victories than McKenzie.
McKenzie began his professional mixed martial arts career with a TKO victory over Brett Held in British Columbia, Canada. This was his only fight to go to a second round in his career prior to the UFC. Under a month later, McKenzie faced Abe Jones, defeating him via triangle choke after little over two minutes.
After taking almost a year away from competition, McKenzie returned to face Benny Mawson, once again in British Columbia, Canada. After 100 seconds, McKenzie caught his opponent in a guillotine choke, taking his record to 3–0. This began his long stretch of victories via guillotine choke. During this near-record setting span, McKenzie fought several times in B.C. and in various locations in Washington. McKenzie also fought in Bahrain on one occasion, taking just four minutes to defeat his opponent with a guillotine choke. Before signing with the UFC, McKenzie had a record of 11–0, with nine successive first-round guillotine choke finishes.
McKenzie then signed with the Ultimate Fighting Championship to appear on The Ultimate Fighter: Team GSP vs. Team Koscheck.
McKenzie competed on the debut episode against Amir Khillah, to get into the house. Prior to the fight, Georges St-Pierre predicted a guillotine choke submission victory for McKenzie. This proved to be correct as McKenzie forced a technical submission victory over Khillah in the opening round.
In the second episode, the team picks were made. Georges St-Pierre picked McKenzie as his sixth pick (twelfth overall).
After getting under coach Josh Koscheck's skin for two weeks, McKenzie was picked to face Marc Stevens; Koscheck's number one pick. Stevens went for an early takedown, but was caught in a guillotine choke submission. With just 18 seconds gone on the clock, Stevens passed out and McKenzie was declared the winner.
In the quarterfinals, McKenzie faced Nam Phan of Team Koscheck. In the second round Phan dropped him with a combo to the body, causing a TKO loss for McKenzie.
McKenzie made his UFC debut at The Ultimate Fighter: Team GSP vs. Team Koscheck Finale against Aaron Wilkinson. He went on to defeat Wilkinson via submission (a guillotine choke applied to Wilkinson's jaw) at 2:03 of round one. McKenzie earned the Submission of the Night award for his performance.
McKenzie made a quick return to the octagon as he replaced Melvin Guillard to face Yves Edwards at UFC: Fight For The Troops 2 on January 22, 2011. After a back and forth battle that saw both men in control, McKenzie lost via rear naked choke in the second round.
McKenzie was expected to face Bart Palaszewski on May 28, 2011 at UFC 130, but was forced off the card with an injury and replaced by Gleison Tibau.
McKenzie fought Vagner Rocha on September 17, 2011 at UFC Fight Night 25. He lost by submission in the second round.
McKenzie was expected to face Michael Johnson on January 28, 2012 at UFC on Fox 2. However, McKenzie was forced out of the bout with an injury and replaced by Shane Roller.
McKenzie was expected to face Aaron Riley on May 15, 2012 at UFC on Fuel TV: Korean Zombie vs. Poirier. However, Riley was pulled from the event and replaced by promotional newcomer Marcus LeVesseur. McKenzie won via submission in the first round.
McKenzie dropped to Featherweight and lost to Chad Mendes via first-round TKO on July 7, 2012 at UFC 148.
McKenzie was expected to face Leonard Garcia on December 29, 2012 at UFC 155. However, McKenzie pulled out of the bout citing an injury and was replaced by Max Holloway.
The bout with Leonard Garcia was rescheduled for April 27, 2013 at UFC 159. McKenzie defeated Garcia via unanimous decision, the first decision win of his career.
McKenzie faced Sam Stout in a Lightweight bout on December 14, 2013 at UFC on Fox 9. He lost the fight via unanimous decision. During the fight, McKenzie wore basketball shorts with the tag still on them, which UFC President called "UFC amateur hour." McKenzie was subsequently released from the promotion.
McKenzie fought at a 180 lb. Catchweight on April 12, 2014 against Mark Dobie at Battle for the Border 3. He won via rear-naked choke submission.
On October 3, McKenzie submitted to Brock Larson in the opening round of the BattleGrounds MMA one-night welterweight tournament.
On December 18, 2014 McKenzie announced his retirement from mixed martial arts.
Two months after announcing his first retirement, it was announced on February 3, 2015, that McKenzie had signed with WSOF. He faced Andrew McInnes at WSOF 18 on February 12, 2015. He lost the fight via disqualification, after a headbutt from McKenzie rendered McInnes unable to continue.
McKenzie was featured in the award-winning mixed martial arts documentary Fight Life, the film is directed by James Z. Feng and released in 2013.Ultimate Fighting Championship
Fight of the Night (One time) vs. Yves Edwards
Submission of the Night (One time) vs. Aaron Wilkinson