Allen made his professional debut on 16 April 2004, scoring a second-round technical knockout (TKO) victory against Troy Lewis at the Cliff Anderson Sports Hall in Georgetown, Guyana.
[3] After compiling a record of 9–0 (5 KOs) he faced Leon Gilkes for the Guyanese super-middleweight title on 27 June 2009 at the Cliff Anderson Sports Hall.
Gilkes was unable to recover in time, prompting the referee to call a halt to the contest, awarding Allen the Guyanese title via second-round TKO.
[4] After two more wins in non-title fights – a six-round unanimous decision (UD) against Amador Acevedo in March 2010[5] followed by a sixth-round TKO against Victor Paz in July[6] – he faced Darnell Boone on 7 August at the Aviator Sports and Events Center in New York City, fighting to a majority draw over eight rounds.
[8] After scoring another nine wins, six by stoppage, he faced rising prospect David Morrell (2–0, 2 KOs) for the vacant WBA interim super-middleweight title on 8 August 2020 at the Microsoft Theater in Los Angeles, California.