Xu Ming, the 44-year-old board chairman of the Dalian Shide Group, died on Friday in a Wuhan jail possibly from a heart attack, state-run Global Times reported.
Xu was arrested for his alleged involvement in fraud in March 2012, and was jailed shortly afterwards with his arrest shrouded in secrecy.
It was never made public when he was arrested, charged and convicted. His prison term also remains unknown.
His body sent back to Dalian in northeast China's Liaoning Province on Sunday and a brief memorial service was held, Beijing-based newspaper The Mirror reported.
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Xu formed the Dalian Shide football club in 2000 and had allegedly owned several football clubs in both top- and second-tier leagues but the Chinese Football Association (CFA) rejected his ownership of additional clubs.
In 2005, Xu was ranked eighth on the Forbes list of wealthiest Chinese the year his football club won both the CFA Super League and CFA Cup.
Bo's wife was convicted of killing a British businessman, and he was accused of accepting nearly USD 3.5 million in bribes from Xu, who also gave the family money to buy an opulent French villa.
Bo was removed from the party and his post in 2012 and was sentenced to life in prison in 2013 for bribery, embezzlement and abuse of power with Xu testifying against him in court.