Rafael Hui, the Hong Kong government's chief secretary from June 2005 to June 2007, has been found guilty of accepting bribes from the city's top property developer Sun Hung Kai Properties.
In the biggest graft trial in Hong Kong's history, Hui was found guilty of three counts of misconduct in public office and two counts of conspiracy to commit misconduct.
He allegedly received HK$8.5m ($1.1m, £704,000, €893,000) in bribes from Sun Hung Kai Properties, and was facing eight charges in all.
Sun Hung Kai Properties co-chairman Raymond Kwok was earlier cleared of all charges, but his brother and fellow co-chairman Thomas Kwok was found guilty of one count of conspiracy to commit misconduct in public office, while cleared of two other charges.
In addition, Sun Hung Kai executive Thomas Chan and businessman Francis Kwan were found guilty of two charges of conspiracy to commit misconduct in public office and conspiracy to offer an advantage to a public servant.
Kwok and Hui, who had been on bail, have been remanded in custody until 22 December when the court will reconvene to hand down sentence. They are facing up to seven years' imprisonment.
The Kwok brothers are running Sun Hung Kai Properties, Hong Kong's second-largest property developer, and they rank third among Hong Kong billionaires with a net worth of $14.4bn, according to Forbes' latest rich list.
The case attracted widespread attention in Hong Kong, where illegal tie-ups between government officials and business magnets have always been a concern.
The former British colony's Independent Commission Against Corruption (ICAC), which arrested the people in 2012, was created by the colonial government, and has been facing criticism over its ineffectiveness to tackle high-profile cases.
Shares of Sun Hung Kai Properties were suspended just before the verdicts were announced. They had risen more than 1% on 19 December.