Peter Chan was charged in 2011 with falsely claiming eccentric billionaire Nina Wang had left her Chinachem Group, worth $10.7 billion, to him after she died at age 69 from cancer.
High Court Justice Andrew Macrae said Chan's efforts to wrest control of Wang's fortune was "shameless, wicked and born of unparalleled greed."
The case involving Chan, a 53-year-old father of three, enthralled Hong Kong with juicy hints at unimaginable wealth mixed with a steamy affair between Chan and the billionaire more than two decades older than he.
Chan's defense tried to prove the relationship was genuine, but the judge said Chan was after Wang's money, particularly after she gave him $387 million while she was still alive.
"I have no doubt you are nothing more than a clever and no doubt beguiling charlatan," Macrae said during the sentencing, calling Chan's forgery all the worse because Wang's fortune was to go to a charitable foundation.
"Instead of benefiting mankind as Nina Wang wanted, the only one to benefit would have been you," Macrae said.
Chan, a former feng shui master, met Wang in 1992 when she hired him to help find her husband, who was kidnapped in 1990 and never found, despite a $33 million ransom.
The judge ordered Chan to pay HK$2 million in legal fees, and said he would serve his three 12-year sentences concurrently.