The charges stem from a luxury penthouse in Shenzhen, across the Chinese border, that the 72-year-old former leader intended to use as a retirement home.
According to RTHK, Justice Andrew Chan told the court the seriousness of the case was due to Tsang's high position and the "breach of trust was an important and significant aspect in his criminality."
Tsang also faces a potential retrial in September, after the jury failed to reach a verdict on a separate charge of bribery.
Misconduct
Tsang was accused of having a conflict of interest over the purchase of the flat, which he did not reveal.
While in negotiation with property tycoon Bill Wong to buy the apartment, Tsang approved a digital broadcast license, and other requests, from Wave Media, in which Wong held a 20% stake.
Last week, a jury found that Tsang had deliberately concealed his negotiations with Wong and found him guilty of "misconduct in public office."
"It encompasses any serious misuse of power or position by public officials even in the absence of evidence that they have received a bribe."
CNN's Mark Lu contributed to this story.