The decision capped a stunning fall for the country's first female leader, who rode a wave of lingering conservative nostalgia for her late dictator father to victory in 2012, only to see her presidency crumble as millions of furious protesters filled the nation's streets.
Two people died during protests that followed the ruling. Police and hospital officials said about 30 protesters and police officers were injured in the violent clashes near the court, which prompted Prime Minister Hwang Kyo-ahn, the country's acting head of state, to plead for peace and urge Park's angry supporters to move on.
The ruling opens Park up to possible criminal proceedings — prosecutors have already named her a criminal suspect — and makes her South Korea's first democratically elected leader to be removed from office since democracy replaced dictatorship in the late 1980s.
It also deepens South Korea's political and security uncertainty as the country faces existential threats from North Korea, reported economic retaliation from a China furious about Seoul's cooperation with the U.S. on an anti-missile system, and questions in Seoul about the new Trump administration's commitment to the countries' security alliance.
Park's "acts of violating the constitution and law are a betrayal of the public trust," acting Chief Justice Lee Jung-mi said. "The benefits of protecting the constitution that can be earned by dismissing the defendant are overwhelmingly big. Hereupon, in a unanimous decision by the court panel, we issue a verdict: We dismiss the defendant, President Park Geun-hye."
Lee accused Park of colluding with longtime confidante Choi Soon-sil to extort tens of millions of dollars from businesses and letting Choi, a private citizen, meddle in state affairs and receive and look at documents with state secrets. Those allegations were previously made by prosecutors, but Park has refused to undergo any questioning, citing a law that gives a sitting leader immunity from prosecution.
It is not clear when prosecutors will try to interview with her.
Park won't vacate the presidential Blue House on Friday as her aides are preparing for her return to her private home in southern Seoul, according to the Blue House. Park wasn't planning any statement on Friday, it said.
Park's lawyer, Seo Seok-gu, who had previously compared Park's impeachment to the crucifixion of Jesus Christ, called the verdict a "tragic decision" made under popular pressure and questioned the fairness of what he called a "kangaroo court."
South Korea must now hold an election within two months to choose Park's successor. Liberal Moon Jae-in, who lost to Park in the 2012 election, currently enjoys a comfortable lead in opinion surveys.
Pre-verdict surveys showed that 70 to 80 percent of South Koreans wanted the court to approve Park's impeachment. But there have been worries that Park's ouster would further polarize the country and cause violence.
Sensing history, thousands of people — both pro-Park supporters, many of them dressed in army-style fatigues and wearing red berets, and those who wanted Park gone — gathered around the Constitutional Court building and a huge public square in downtown Seoul.
A big television screen was set up near the court so people could watch the verdict live. Hundreds of police were on hand, wearing helmets with visors and black, hard-plastic breastplates and shin guards. The streets near the court were lined with police buses and barricades.
Some of Park's supporters reacted with anger after the ruling, shouting and hitting police officers and reporters with plastic flag poles and steel ladders, and climbing on police buses. Anti-Park protesters celebrated by marching in the streets near the presidential Blue House, carrying flags, signs and an effigy of Park dressed in prison clothes and tied up with rope.
The Seoul Metropolitan Police Agency said two people died while protesting Park's removal. An official from the Seoul National University Hospital said that a man in his 70s, believed to be a Park supporter, died from head wounds after falling from the top of a police bus.
An official from the Kangbuk Samsung Hospital in Seoul said another man brought from the pro-Park rally died shortly after receiving CPR at the hospital. The hospital official couldn't immediately confirm the cause of death.
In a televised speech, Hwang said "there would be people who feel they cannot understand or accept (the court ruling), but it's now time to move on and end all conflict and standoff."
Park's parliamentary impeachment in December came after weeks of Saturday rallies that drew millions who wanted her resignation. Overwhelmed by the biggest rallies in decades, the voices of Park supporters were largely ignored. But they've recently regrouped and staged fierce pro-Park rallies since.
Prosecutors have arrested and indicted a slew of high-profile figures over the scandal, including Park's confidante Choi, top Park administration officials and Samsung heir Lee Jae-yong.
Since Park is no longer in power, prosecutors can summon, question and possibly arrest her. Her critics want to see Park appear on TV while dressed in prison garb, handcuffed and bound like others involved in the scandal. But some analysts worry that could create a backlash by conservatives ahead of the presidential vote.
Among the most serious problems facing South Korea is China's retaliation against the deployment of a U.S. high-tech missile defense system in the South. Ties with North Korea are terrible, with Pyongyang seeking to expand its nuclear and missile arsenal. Japan hasn't sent back its ambassador, who was recalled two months ago over history disputes. South Korea also worries about the Trump administration asking for a greater financial contribution for U.S. troop deployment in the South.
Hwang has led the government as acting leader since Park's impeachment, and he will continue to do so until South Korea elects new president. Some media reports said Hwang might run for president as a conservative candidate. If that happens, he would have to resign to run and a deputy prime minister would become interim leader.
In 2004, then President Roh Moo-hyun was impeached by parliament for alleged election law violations and incompetence, but the Constitutional Court later reinstated his power.