Through Matchroom, Hearn is also involved in many sports including boxing, snooker, darts, pool, tenpin bowling, golf, table tennis and fishing.

[3] After qualifying as an accountant, Hearn took over the role of finance director to a design company based in Kensal Green, called Deryck Healey Associates (circa 1973).

[3] Hearn and business partner Deryck John Healey then bought Lucania Billiard Halls, which formed the basis of his future career, promoting snooker via colour television.

Later Matchroom snooker players include Terry Griffiths, Dennis Taylor, Willie Thorne, Neal Foulds, Jimmy White, Cliff Thorburn and Ronnie O'Sullivan.

In June 2010, following a vote by the members, Hearn took over a 51% controlling interest in the organisation's commercial business World Snooker Limited with a view to revitalising the game.

[3] Hearn has since promoted many leading British and Irish boxers, including Chris Eubank, Nigel Benn, Lennox Lewis, Naseem Hamed, Steve Collins and Herbie Hide.

[3] Hearn withdrew his boxers Herbie Hide and Steve Collins from the High Noon in Hong Kong event at the last minute, scheduled on 22 October 1994, when promoter John Daly could not come up with the purses.

In the trailer for the film Hearn is seen dismissing claims made that boxer Steve Collins was hypnotised by Cult-leader Tony Quinn to not feel pain as "What a load of rubbish".

Before Hearn's takeover the club was facing a financial disaster due to the collapse of the then chairman Tony Wood's coffee business in Rwanda at the time of the Rwandan genocide.