The vote took place as hundreds of thousands took to the streets of Seoul in rival rallies for and against Yoon, who launched a failed attempt to impose martial law on December 3.
Out of 300 lawmakers, 204 voted to impeach the president on allegations of insurrection while 85 voted against. Three abstained, with eight votes nullified.
With the impeachment, Yoon has been suspended from office while South Korea’s Constitutional Court deliberates on the vote.
If it backs his removal, Yoon will become the second president in South Korean history to be successfully impeached.
Prime Minister Han Duck-soo — now the nation’s interim leader — told reporters he would “devote all my strength and efforts to ensure stable governance”.
Two hundred votes were needed for the impeachment to pass, and opposition lawmakers needed to convince at least eight parliamentarians from Yoon’s conservative People Power Party (PPP) to switch sides.
“Today’s impeachment is the great victory of the people,” opposition Democratic Party floor leader Park Chan-dae said following the vote.
K-pop singer Yuri of the band Girls’ Generation — whose song “Into the New World” has become a protest anthem — said she had pre-paid for food for fans attending the demonstration.
“Stay safe and take care of your health!” she said on a superfan chat platform.
One protester said she had rented a bus so parents at the rally would have a place to change diapers and feed their babies. Another said they had initially planned to spend their Saturday hiking. “But I came here instead to support my fellow citizens,” Kim Deuk-yun, 58, told AFP.
There is precedent for the court to block impeachment, however. In 2004, then-president Roh Moo-hyun was removed by parliament for alleged election law violations and incompetence, but the Constitutional Court later reinstated him.
Yoon remained unapologetic and defiant as the fallout from his disastrous martial law declaration deepened and an investigation into his inner circle has widened.
His approval rating — never very high — plummeted to 11 percent, according to a Gallup Korea poll released yesterday .The same poll showed that 75 percent supported his impeachment.
CHANNEL