Simpson made his professional debut in 2019 against seasoned journeyman Elvis Dube at
Doncaster Racecourse, winning a points decision. In October of the same year, Simpson faced and beat Kiril Psonko. A month later, he beat Richard Harrison via technical knockout at the Metrodome, Barnsley. Simpson had two fights in 2021, the first in October against Lewis van Poetsch. The second in December versus Antony Woolery, winning both via technical knockout. Simpson won his first title by stopping Ben Ridings in the second round to claim the
Central Area super-middleweight title at the Leisure Centre in
Oldham on 1 October 2022. In February 2023, Simpson signed an exclusive promotional agreement with
Boxxer. Simpson made his Boxxer debut in March 2023 against Celso Neves,winning via technical knockout. In July, he beat Boris Crighton via unanimous decision. His third fight of the year came against Jose de Jesus Macias, with Simpson winning via unanimous decision after scoring a knockdown in the eighth round. Simpson won the
British and
Commonwealth super-middleweight titles against champion
Zak Chelli on 3 August 2024 in
Barnsley at Simpson's childhood football club
Barnsley F.C.'s stadium
Oakwell. The fight, billed as Battle Lines, was won by Simpson via unanimous decision. He made a successful first defense of his titles by stopping Steed Woodall in round two of their bout at
Park Community Arena in Sheffield on 11 January 2025. Three weeks later, on 1 February 2025, he defended his Commonwealth title against Ghanaian boxer Elvis Ahorgah at
Wembley Arena in London, stopping his opponent in the fifth round. Simpson faced
Ivan Zucco for the vacant
European super-middleweight title at
Oakwell in
Barnsley on 7 June 2025. He was knocked to the canvas in the first and third rounds, but recovered to win by stoppage when he felled his opponent three times in the 10th round. Simpson put his European, British and Commonwealth super-middleweight titles up for grabs against
Troy Williamson at
First Direct Arena in
Leeds on 20 December 2025. He was sent to the canvas four times in the 10th round and lost via technical knockout when the referee waived the fight off following the fourth knock down. == Personal life ==