[3] He is the chairman and largest single shareholder of Premier League football team West Ham, following the death of business partner David Gold in 2023.

They expanded into sex shops, adult magazines and several low-budget blue movies, making Sullivan a millionaire by the age of 25.

In the late 1970s, he produced several low-budget British sex movies including Come Play with Me (1977) (directed by Harrison Marks).

In 2007, Sullivan expressed his first desire to sell his share in Birmingham City and openly admitted three reasons for a possible departure.

After 16 years at the club, Birmingham managing director Karren Brady and chairman David Sullivan agreed to step down from their posts on completion of Carson Yeung's takeover in Autumn 2009.

[11] The Birmingham manager at the time, Alex McLeish, praised the Sullivan-Gold duo in the media for providing the club with financial stability, stating he respected them a lot for what they had achieved.

Less than one year later in January 2010, he and David Gold acquired a 50% share in West Ham United giving them operational and commercial control and valuing the Premier League club at £105 million.

David lived 50 yards from the ground for 20 years of his life and played for West Ham's youth team.

[15] As part of his long-term aspirations for the club, Sullivan backed West Ham's bid to move into the Olympic Stadium in Stratford.

[16] On 22 March 2013, West Ham secured a 99-year lease deal, with the stadium planned to be used as their home ground from the 2016–2017 season.

[17] In July 2013, Sullivan became the largest single shareholder of West Ham United acquiring a further 25% of shares in the club.

[20] On 26 March 2018, an HMRC tax tribunal ruled that Sullivan had used West Ham United to avoid paying £700,000 tax for his own family business, Conegate Ltd. Sullivan used Conegate to buy £2 million of shares in the holding company that owns West Ham.

[23] Sullivan has two children, David and Jack with ex-girlfriend Emma Benton-Hughes (formerly known as Eve Vorley while working as a porn actress).

Sullivan celebrated West Ham's promotion to the Premier League in May 2012 by donating a five figure sum to a charity for children with autism.