Leyton Orient chairman Barry Hearn has completed the sale of his stake in the League One club to Italian businessman Francesco Becchetti.
Sports promoter Hearn, 66, took over the O's during the 1994-95 season.
But he has now sold his company Matchroom Sport Ltd's 90% shareholding in the club to Becchetti, 47, who becomes Orient's new chairman.
Hearn's decision follows the club's loss on penalties to Rotherham in last season's League One play-off final.
Hearn, his son Eddie, Steve Dawson and David Dodd have all resigned from the club's board, while Matthew Porter has stood down as chief executive but will remain as a director.
Becchetti, who is the head of the Becchetti Energy Group, has previously been linked to takeovers of Championship club Reading and Italian Serie B side Bologna.
Dagenham-born Hearn, who first attended an Orient game aged 11, is also the chairman of World Snooker and the Professional Darts Corporation.
Hearn had wanted Orient to move from Brisbane Road to the Olympic Stadium, but the London Legacy Development Corporation appointed West Ham United as their preferred bidders and, in March 2013, the Premier League side were awarded the right to occupy the stadium.
Orient settled a dispute with the Premier League over their decision to allow West Ham to play in the stadium when they reached a "confidential agreement" last week.