Lee was also convicted of embezzlement, hiding assets overseas, concealing criminal profits and perjury.
Samsung made no comments on the sentence, but Lee's lawyers said they are appealing.
The court also said the amount included $6.4 million to sponsor the equestrian career of Choi's daughter.
Park was removed from office in March.
Lee may be kept in detention for a maximum of four months while a court considers his appeal. Considering the regulations of the Aggravated Punishment of Specific Crimes Law, which stipulate that even a bribe of over 100 million won (US $90,000) means facing over 10 years in prison, if Park is found guilty on this count, it will be hard for her to avoid a severe sentencing.
The closely-watched verdict is the latest convulsion in a political scandal that prompted millions of South Koreans to protest last fall, culminating in the ouster and arrest of Park as well as the arrests of Choi and Lee.
"This case is a matter of Lee Jae-yong and Samsung Group executives, who had been steadily preparing for Lee's succession. bribing the president", Seoul Central District Court Judge Kim Jin-dong said, using Lee's Korean name. "We hope that it would pave the way to end persistent government-business collusion, which has hampered society from moving forward", its spokesman Yoon Young Chan said.
Lee Jae Yong's father, who remains Samsung chairman, was previously convicted of bribery, tax and other offences himself, and the scion's grandfather also had brushes with the law, but neither was ever jailed.
Park's relationship with Choi and her father Choi Tae-min has always been controversial in Korea. Lee has two sisters, but neither has been heavily involved in Samsung Electronics, which is widely regarded as the center of the Samsung empire.
Lee's imprisonment as an "unprecedented challenge" and encouraged staff to continue working hard as they wait for "the truth to come to light".
"As a legal professional, I can not possibly accept any part of the lower court's guilty verdicts", said Song Wu-cheol, lead defense attorney, who added, "I am confident that the appeals court will definitely find the defendants not guilty on all counts".
Lee has not plead guilty to the charges brought against him.
Traditionally in South Korea, powerful executives who have been convicted of crimes have managed to avoid big prison terms through commuted sentences and even presidential pardons. Some were pardoned and others got sentences reduced on appeal.