In 2005, two businessmen, Lin Cheuk-fung and Cheung Chi-tai, offered Yeung the chance to invest in junket operator Neptune Group. Junket operators bring in gamblers from mainland China and offer lines of credit and often collect debts from them.
A Reuters' 2010 special report found links between Cheung and organised criminal gangs, or triads, and a casino run by gambling goliath Las Vegas Sands in Macau.
While Cheung hasn't been convicted of any triad-related crimes, his organised crime affiliation was corroborated by U.S.authorities and former and current police officials.
The Hong Kong court heard how Yeung had received hundreds of deposits of unclear provenance for what Yeung claimed to be winnings from his gambling.
These included cash payments from Cheung and a tranche of cheques worth HK$72.5 million ($9.34 million) from Macau casino operator Sociedadede Jogos de Macau S.A., part of SJM Holdings Ltd, which is owned by gambling tycoon Stanley Ho.
(Read more: Is Italian soccer giant AC Milan up for sale?)
Yu, the police investigator,admitted many aspects of the case remain unsolved including, crucially, the origination of much of the laundered cash. But she said that investigations would continue in a bid to bring others to justice.
The judge said that while Yeung wasn't the mastermind or "director" of a laundering scheme, "without his considerable skills in share dealings and connections to the Macau casinos, the laundering could not have gone on for such a long time and on such a large scale."
Yeung, who bought Birmingham City Football Club in 2009, stepped down last month as head of the club and its holding company, Birmingham International Holdings Ltd.
After Yeung was convicted, club officials said the verdict would have no impact on its day-to-day operations.
Follow us on Twitter: @CNBCWorld