Cook turned professional in December 1998 in Hertfordshire, England. In his debut Cook defeated English journeyman Sean Grant with a first round knockout.
After fifteen fights in December 2001 unbeaten Cook beat Argentinian Marcelo Gabriel Ackermann for the vacant and lightly regarded WBF Intercontinental super featherweight title. He defended the strap twice before getting his chance to compete for the Commonwealth belt.
British, Commonwealth and European Champion
In February 2003 Cook fought the Zimbabwaen Meshack Kondwani for the vacant Commonwealth Featherweight belt. He defended twice against Africans David Kiilu and Anyetie Laryea before taking on Cyril Thomas for the European belt also at featherweight. He won the fight with a 9th round knockout, he made one defence before taking on British champion Dazzo Williams in June 2005. The fight took place at the Goresbrook Leisure Center in Dagenham and was significant because it meant the British, Commonwealth and European titles were all on the line in a winner take all contest. Cook stopped Williams in the 2nd round thus holding all three belts at the same time.
Cook defended his European title once more beating Yuri Voronin on points over 12 rounds again in Dagenham. After that he decided to concentrate on his ambition to win a real 'world' title and set his sights on current holder of the WBO Featherweight belt Scott Harrison. The fight was set for December 2006 in what would have been an England vs Scotland clash for a world belt, it never happened however as Harrison pulled out and decided to vacate the title citing difficulties making the weight. It hadn't helped that Harrison had also spent 13 weeks in a Spanish prison prior to the bout and had only been released in November. Cook was left frustrated and instead of fighting for the world title on the card he ended up beating Harry Ramogoadi in an eight rounder.
In July 2007, Cook finally got his chance and took on American Steve Luevano for the now vacant World Boxing Organization's (WBO) belt. The fight took place at the O2 Arena in London and ended disappointingly for Cook as he was knocked down 5 times and finally stopped in the 11th round it was his first defeat as a professional.
Cook got another opportunity to fight for the WBO belt in September 2008 when he decided to move up a weight division and challenge Alex Arthur for the WBO Super-Featherweight title. The fight took place at the MEN Arena in Manchester and was the chief support to Amir Khan's ill-fated match up with Colombian Breidis Prescott when he was knocked out within a minute. Cook beat Arthur over 12 rounds to win a unanimous decision. The parallels were striking between the fighters as Arthur was also a former British, Commonwealth and European champion at the higher weight, he had also been beaten only once before.After the fight Arthur claimed he had been "robbed" and also alleged that Cook had gone up to him after the fight and said "You're a great champion, you won the fight well done" thus compounding his sense of shock when the verdict was announced.On March 14, 2009, Cook will defend this championship against the WBO's mandatory challenger, Román Martínez.