Lee was found guilty of bribing Park, perjury, concealing criminal profits, embezzlement, and hiding assets overseas. It is by far the largest of the chaebols, the family-controlled firms that dominate Asia's fourth-largest economy, which some South Koreans self-mockingly dub the "Republic of Samsung".
The defense had denied the charges, saying Samsung was pressured by Park to make the donations under duress, and that Lee was not aware of them and did not approve them.
It seems unlikely that Lee will get the same government favors as his father, Lee Kun-hee, Samsung's chairman, who was convicted two times of bribery and tax evasion but who served no jail time after being pardoned twice.
Samsung, founded in 1938, epitomises South Korea's economic resurgence after the Korean War in the 1950s.
Lee denied any involvement and any wrongdoing in the scandal and his lawyer said that he would appeal the conviction.
"The entire verdict is unacceptable", Song said, adding that he was confident his client's innocence would be affirmed by a higher court.
Supporters of the ousted president staged a rally outside the court on Friday to demand Lee's release, facing off against another group of protesters who instead demanded punishment for the Samsung boss.
He stood accused of offering millions of dollars to former president Park Geun-hye, who is now undergoing her own trial, and business partner Choi Soon-sil, in exchange for favourable businesss conditions. It's part of a huge influence-peddling scandal that brought down the government of former President Park Geun-hye.
Concluding a five-month trial, a panel of three judges found Lee, as well as four other leaders, to be guilty of paying bribes totaling 43.3 billion won (US$38.3 million).
At a parliamentary hearing in December, Lee told lawmakers said he had not been informed of Samsung's bankrolling of the daughter's equestrian training, and that he was unaware of the Chois.