Arnfield made his professional debut on 26 October 2007, scoring a first-round stoppage over Lewis Byrne.
For his next seventeen fights over a span of eight years, Arnfield went undefeated and won mainly four- and six-round points decisions.
On 14 February 2015, Cello Renda handed Arnfield his first loss, via three-round split decision, as part of the tournament semi-finals of Prizefighter 34: The Middleweights III.
[1] Later in the year, on 14 November, Arnfield fought for his first major regional championship—the British middleweight title—but lost a twelve-round unanimous decision to defending champion Nick Blackwell.
[2] On 25 March 2017, Arnfield beat Brian Rose by unanimous decision in their 12 round contest.