Born and raised in Suffolk, Allen began training in mixed martial arts as a teenager and took part in several amateur fights before turning professional in 2012.
He made his professional debut competing as a featherweight for various regional promotions across Great Britain, including a stint in Cage Warriors. He was able to compile a record of 9 – 1 in his first three years along the way. After his TKO stoppage of Paul Cook in November 2014, Allen signed with the UFC.
Ultimate Fighting Championship
Allen made his promotional debut on 20 June 2015 as a short notice replacement filling in for an injured Mike Wilkinson against Alan Omer at UFC Fight Night 69. After probably dropping the first two rounds, Allen won the fight via submission in the third round. He was also awarded a Performance of the Night bonus. Allen next faced Yaotzin Meza on 27 February 2016 at UFC Fight Night 84. He won the fight by unanimous decision. Allen was expected to face Mirsad Bektic on 8 October 2016 at UFC 204. However, due to injury, Allen withdrew from the fight and was replaced by Russell Doane. Allen faced Makwan Amirkhani on 18 March 2017 at UFC Fight Night 107. He won the fight by split decision. Allen was scheduled to face Enrique Barzola at UFC 220 on 20 January 2018. However, Allen was pulled from the fight on January 11 due to alleged visa issues which restricted his ability to travel. Following this announcement, It was determined that Allen would be replaced by Matt Bessette at UFC 220. Allen faced Mads Burnell on 27 May 2018 at UFC Fight Night 130. He won the fight via front choke submission in the third round. This win earned him the Performance of the Night award. Allen was expected to face Gilbert Melendez on 30 November 2018 at. However, Melendez pulled out of the fight on 5 November and was replaced by Rick Glenn. In turn, Allen pulled out of the fight on 16 November citing a cut he received while training. Allen faced Jordan Rinaldi on 16 March 2019 at UFC Fight Night 147. He won the fight by unanimous decision. Allen faced Gilbert Melendez on 6 July 2019 at UFC 239. He won the fight via unanimous decision. Allen was expected to face Josh Emmett on January 25, 2020 at UFC Fight Night 166. However Emmett was pulled from the event for an undisclosed reason, and he was replaced by Nik Lentz whose original featherweight opponent also dropped out of the event. Allen won the fight via unanimous decision.
Personal life
Allen was issued a five-month suspended sentence after he pled guilty to affray, for his role in a 23 December 2016 brawl near Ipswich which left a man and five women injured. As a result, Allen could face travel restrictions due to the conviction.
Championships and accomplishments
Ultimate Fighting Championship
*Performance of the Night vs. Alan Omer and Mads Burnell
