McKenzie's professional career begun on 6 March 2003, with a victory over fellow debutant Leigh Alliss at Ashton Gate the home of Bristol City.
One significant result during the year however saw him score a shock upset win over the then undefeated English champion Steven Spartacus in a fight which was only over six rounds and did not have the title on the line.
[1] Over the course of 2005 and 2006, McKenzie was able to maintain an eight fight winning run culminating in a successful challenge against Peter Haymer for the vacant Commonwealth light heavyweight title on 24 November 2006.
McKenzie returned to action a year and a half later following the loss to Salem only to once again drop a close points decision this time to Bob Ajisafe at the Leigh Indoor Sports Center on 17 April 2009.
[6] McKenzie followed up his success on the Prizefighter with a win over Billy Boyle on 5 February 2010[1] before, on 9 December 2010, earning a challenge for his old Commonwealth light heavyweight title at the Echo Arena in Liverpool.