His success led him to join the paid ranks and, in November 2000 his first fight, against Richmon Asante in Manchester, ended in a win that sent him on a run of 11 more pro fights undefeated. He was able to contest the British super-featherweight title in October 2002 against Steve Conway at Braehead. Victory over Conway was followed by two further successful defences and one more would let him keep the Lonsdale belt for good.
Enter Michael Gomez. The hard-hitting Mancunian took on Arthur at Meadowbank in October 2003. Arthur opted to go toe to toe with Gomez and was knocked out in the fifth.
In March 2004, he stopped Michael Kizza in the first round to take the IBF Inter-Continental super-featherweight title. He made two defences before taking a shot at Commonwealth super-featherweight champion Craig Docherty. Knocking Docherty out in the ninth saw Arthur take the British and Commonwealth titles.
Victories against European super-featherweight champion, Boris Sinitsin and fellow Scot Ricky Burns, led Arthur to win the interim WBO super-featherweight title with a stoppage success over Koba Gogoladze in July 2007. Arthur then set his sights on Dominican Joan Guzmán who held the full title. Guzmán wanted to move up a weight division and chose not to fight Arthur. Therefore, the Scot was recognised as the organisation’s world champion. Arthur surrendered the title in his very next fight, however, losing a unanimous points decision to England’s Nicky Cook in Manchester September 2008.