The Ultimate Fighter

In January 2013, it was revealed that Casey was a cast member of The Ultimate Fighter: Team Jones vs. Team Sonnen. He won his preliminary bout over Eldon Sproat via rear naked choke. Casey was selected by coach Sonnen as his sixth pick (eleventh overall). In the next round, Casey was pitted against coach Jones' fifth pick Collin Hart. He lost the bout via unanimous decision.

Casey was then given a second chance when he was chosen as Team Sonnen's wildcard. He fought against Team Jones' Bubba McDaniel. Despite controlling the first round, Casey lost via TKO at the end of the second round when he was unable to answer the bell for the third round. Many people, including Dana White, were shocked Kevin could just quit like that. Casey attributed this to difficulties relating to acute kidney injury from his drastic weight cut for his bout.

Ultimate Fighting Championship

On April 9, 2013, it was announced that Casey would face fellow season 17 alumni Josh Samman at The Ultimate Fighter 17 Finale.^[5] He lost the fight via TKO in the second round. Following the loss Casey was released from the promotion.^[6]

Resurrection Fighting Alliance

Following his release from the UFC, Casey signed with Resurrection Fighting Alliance (RFA).^[7] He made his RFA debut on August 16, 2013, at RFA 9 against Casey Ryan.^[8] He won the fight by unanimous decision. He fought next on January 24, 2014, against former UFC veteran Eddie Mendez. He won that fight via TKO (Elbows) in the first round.

Metamoris

Casey replaced Vinny Magalhães on 30 minutes notice at Metamoris 3, a submission-only jiu-jitsu competition, in Los Angeles on March 29, 2014. Casey was submitted by Keenan Cornelius via heel hook.^[9][10] In 2012, Casey himself had to pull out of a scheduled Metamoris competition, making his 2014 appearance his first participation with the organization.

Casey was scheduled to face Vinny Magalhaes at Metamoris 5, however was forced to withdraw just a week out from the November 22, 2014, competition due to a bloodclot in his calf that required surgery.^[11]

Return to UFC

Following his championship win at Resurrection Fighting Alliance 15, Casey was re-signed by the Ultimate Fighting Championship. He faced Bubba Bush at UFC 175 on July 5, 2014.^[12] He won the fight via TKO early in the first round due to a punch that dropped his opponent and subsequent elbows on the ground. However, Casey later failed a post-fight drug test for drostanolone, a form of anabolic steroid.^[13] Later, he was suspended for a year and fined $5,600 by the Nevada Athletic Commission.^[14]

Returning from his suspension, Casey faced Ildemar Alcântara on July 15, 2015, at UFC Fight Night 71.^[15] He won the fight by unanimous decision.^[16]

Casey faced Antônio Carlos Júnior on December 10, 2015, at UFC Fight Night 80.^[17] The bout was deemed a No Contest just 11 seconds into the first round when Júnior accidentally poked Casey in both eyes and Casey was unable to continue.^[18]

Casey faced Rafael Natal on January 30, 2016, at UFC on Fox 18.^[19] He lost the fight via TKO in the third round.^[20]

Casey next faced Elvis Mutapčić on June 4, 2016, at UFC 199.^[21] The fight ended in a split draw.^[22]

Casey faced Sam Alvey on August 27, 2016, at UFC on Fox 21.^[23] He lost the fight via TKO in the second round.^[24]

On October 21, 2016, the UFC announced that they had cut Casey from the promotion.^[25]

Bellator MMA

On November 1, 2016, it was announced that Casey had signed with Bellator. He faced Keith Berry at Bellator 170 on January 21, 2017. The bout ended in a majority draw.

Casey faced Chris Honeycutt at Bellator 182 on August 25, 2017. He lost the fight via TKO in the second round.^[26]

On February 20, 2018, it was announced that Bellator had released Casey from the promotion.^[27]

Mixed martial arts exhibition record