The Seoul Central District Court sentenced Choi, who is at the center of the influence-peddling scandal that led to the impeachment of former President Park, to a 20-year imprisonment and fined Choi 18 billion won (16.6 million US dollars).
The decades-long confidante of the impeached president was taken into custody in November 2016, and indicted in the same month for 18 counts of corruption.
The court ruling said Choi abused the presidential power and forced large conglomerates to donate tens of millions of US dollars to two nonprofit foundations controlled by her.
Choi received 7.29 billion won (6.7 million US dollars) in bribes from Samsung Electronics Vice Chairman Lee Jae-yong, an heir apparent to Samsung Group, the country's biggest family-controlled conglomerate.
Special prosecutor Park Young-soo and state prosecutors claimed Choi received a combined 43.3 billion won (39.9 million US dollars) from the Samsung heir who was released from prison in the appeals' court ruling last week.
An Chong-bum, former senior secretary for Park, was sentenced to six years in jail as he was identified as an accomplice to Choi and Park. An was fined 100 million won (92,225 US dollars) for taking bribes.
Lotte Group Chairman Shin Dong-bin got a jail term of two and a half years for bribery. Shin was immediately put under custody in the courtroom.
The court ruled that Lotte provided 7 billion won (6.5 million US dollars) in bribes to one of the Choi-controlled foundations in return for business favors.