Carson Yeung, who last month resigned from positions of power with the English second-tier club, was convicted over charges relating to his handling of 721 million Hong Kong dollars (£55.5 million) using five bank accounts between January 2001 and December 2007.
Prosecutors say the money was "criminal proceeds".
The charges are unrelated to Birmingham City Football Club, which the 54-year-old hairdresser-turned-businessman bought in 2009 for £81.5 million.
Birmingham won the 2011 League Cup, ending 48 years without a major trophy, but despite the victory were relegated from the Premier League the same year. Scot Alex McLeish is a former manager.
Yeung is due to be sentenced on Friday. His father and co-accused, Yeung Chung, died in 2012.