Diakiese began training in mixed martial arts in 2010. He won three British amateur titles while compiling an undefeated record of 9–0 before turning pro. Diakiese has competed in a grappling match, at under 187lbs/85kg division, on the Pantheon 002 event in June 29th 2019, going to a draw against Ben Hills.
After earning four wins in his professional MMA career in regional promotions, Diakiese joined the BAMMA organization in 2014. He fought five times for the promotion over the course of the next year, bringing his record to 9-0 and in the process winning the BAMMA Lonsdale British Lightweight Championship, which he successfully defended twice before signing with the UFC.
Diakiese made his UFC debut against Lukasz Sajewski on 8 October 2016 at UFC 204. After being smothered by his opponent in the first round, Diakiese came back to win the fight by TKO due to knees and punches near the end of the second round. Diakiese returned to face Frankie Perez on 9 December 2016 at. Despite losing the second round, Diakiese would go on to win the bout by unanimous decision. Diakiese faced Teemu Packalén on 18 March 2017 at. Diakiese defeated Packalén via knockout, 30 seconds into the first round. The win earned Diakiese his first Performance of the Night bonus. Diakiese faced Drakkar Klose on 7 July 2017 at. He lost the fight by split decision. Diakiese faced Dan Hooker on 30 December 2017 at UFC 219. He lost the fight via guillotine choke submission in the third round. Diakiese faced Nasrat Haqparast on 22 July 2018 at UFC Fight Night 134. He lost the fight via unanimous decision. Diakiese faced Joseph Duffy on 16 March 2019 at UFC Fight Night 147. He won the fight by unanimous decision. In May 2019, Diakese revealed on his social media that he had signed a new, multi-fight contract with the UFC. Diakiese faced Lando Vannata on 28 September 2019 at UFC on ESPN+ 18. He won the fight via unanimous decision. Diakiese was scheduled to face Stevie Ray on 21 March 2020 at. However, Ray was removed from the card late-January for undisclosed reasons. Diakiese was expected to remain on the card against promotional newcomer Jai Herbert. Due to the COVID-19 pandemic, the event was eventually postponed. Instead Diakiese was scheduled to face Alan Patrick on 19 July 2020 at UFC Fight Night 172. However, on June 14, Patrick withdrew from the event for unknown reason and he was replaced by Rafael Fiziev. He lost the fight via unanimous decision. This fight earned him the Fight of the Night award.
Personal life
Diakiese was the first UFC fighter to pose for Gay Times Magazine, an LGBT publication where his view on LGBT community was "As people, we are all one".
