The verdict was broadcast live and represents the culmination of a scandal which rocked the country, fuelling rage against political and business elites.
Park, who was also fined 18bn won (£12m, $17m), faced a string of corruption charges.
The former leader was not in court on Friday for the verdict.
She has boycotted her trial hearings and has previously accused the courts of being biased against her. She has also denied all wrongdoing and has said she will appeal her sentence.
Judge Kim Se-yoon said Park had shown "no sign of repentance" after causing "massive chaos" in the country.
"We cannot help but sternly hold her accountable," the judge said.
South Korea's presidential residence, the Blue House, issued a statement after the verdict calling it a "heartbreaking event for the nation".
"A history that is not remembered is bound to be repeated," it read.
The move by the authorities to allow Friday's verdict to be broadcast live was unprecedented, but they cited extraordinary public interest in the case.
What was she convicted of?
Park was found guilty of 16 out of 18 charges, most of which related to bribery and coercion.
The court ruled that she had colluded with her close friend, Choi Soon-sil, to pressure conglomerates such as electronics giant Samsung and retail chain Lotte to give millions of dollars to foundations run by Choi.
She was also convicted of forcing companies to sign lucrative deals with firms owned by Choi and donate gifts to Choi and her daughter.
In addition, Park was found guilty of leaking confidential presidential documents to Choi.
She has seven days to file an appeal.
What led to her downfall?
A friendship lies at the heart of the undoing of South Korea's first female president.
Park and Choi were childhood friends and Choi swiftly became the leader's most trusted confidante.
But their relationship latterly came under intense public scrutiny and the charge is that Choi had undue influence over a nation's affairs through her connection with Park.
After a prolonged series of hearings and months of street protests calling for her resignation, Park was finally removed from office in March 2017, making her the first democratically-elected president to be impeached.
She was arrested shortly afterwards, and has been in detention ever since.
Who else was caught up in this?
Some of the biggest South Korean companies and their leaders have been drawn into the scandal, as well as numerous figures from the entertainment world and government servants.
Samsung's de facto leader Lee Jae-yong, also known as Jay Y Lee, was singled out in particular after details emerged that he had given a horse to Choi's daughter Chung Yoo-ra, who is an equestrian.
He was sentenced to jail, but only served five months before he was freed, when an appeals court reduced and suspended his sentence.
Ms Chung has also faced scrutiny, and was extradited from Denmark to South Korea last year to face questioning.
Is this unusual in South Korea?
Park, the country's first female leader, was also the first democratically-elected president to be impeached.
But she is not the only former president to have been arrested for corruption.
No comments: