With South Koreans divided over the sacking of their leader Park Geun Hye, Acting President Hwang Kyo Ahn sought to narrow the rift, urging the people to accept the top court's ruling and calling for unity to ensure stability.
"The country has to elect a new president within a short span of 60 days... If unity does not serve as our foundation after we sort out the current chaos, it would be impossible to stabilise state affairs and manage the presidential election in a fair manner," he said in a televised national address.
He also urged protesters to refrain from further conflict, after two pro-Park supporters died during clashes with riot police.
In a unanimous decision yesterday morning, all eight justices of the Constitutional Court upheld Ms Park's impeachment by Parliament last December. Acting Chief Justice Lee Jung Mi said the court accepted the findings of the prosecution's probe that said Ms Park abused her power and leaked official secrets to allow her confidante Choi Soon Sil to meddle in state affairs and make personal gains from it.
Key points of Constitutional Court ruling
• The court accepted most of the findings of a prosecution investigation, which revealed that numerous official documents, including state secrets, were leaked from the presidential office to Ms Park Geun Hye's long-time friend Choi Soon Sil, according to Yonhap News Agency.
• It ruled that Ms Park helped Choi establish foundations she later used to collect "donations" from local conglomerates, including Samsung Group.
• It ruled that Ms Park abused her status and power for Choi's personal gains. It said Ms Park thoroughly concealed Choi's interference with state affairs, denying it whenever suspicions were raised.
• The court said Ms Park's actions were not a fair execution of official duty, and violated the Constitution, the Public Servants Law and Public Servants' Ethics to the extent she deserves to be unseated.
• Ms Park also faced criticism for her alleged inaction during a 2014 ferry sinking that killed more than 300 people, mostly high school students. The court said that whether the president neglected her duties during the sinking has nothing to do with the impeachment.
• The court said it did not see enough evidence the president had abused her authority in firing government officials.
Ms Park is also accused of colluding with Choi to extort millions of dollars from conglomerates, including Samsung, to fund two foundations that Choi had set up allegedly for her own gain.
"The President has let the people down and her actions are a grave violation of the law and Constitution," Justice Lee said in the ruling, which is final and irreversible.
"What she did has severe negative effects and repercussions, and we believe there are more benefits in expelling her from office."
The top court's ruling, which was televised live, marks the downfall of the country's first female president. The scandal broke last October, triggering massive protests demanding Ms Park's resignation. Her presidential duties were suspended after Parliament impeached her last December.
A presidential spokesman yesterday said Ms Park would continue to reside in the presidential Blue House and no date has been fixed for her to move to her private residence in the upscale Gangnam district.
Ms Park will have to face a criminal probe, according to local media, though some analysts noted that impeachment is punishment enough.
The ruling Liberty Korea Party, formerly known as Saenuri, apologised to the people, saying it "failed to fulfil our duty as the ruling party and failed to protect the dignity and pride of South Korea".
Defence Minister Han Min Koo called for military vigilance against any possible provocation from the North, while the Unification Ministry said it will continue its policy of peaceful unification. Foreign Minister Yun Byung Se also promised no change in policy direction.
Analysts say the court made the right decision in upholding the impeachment vote. Polls have shown that over 70 per cent of respondents want Ms Park sacked.
"The ruling is very straightforward. It's very clear that former president Park operated out of the boundaries of the Korean Constitution," said political scientist Kim Jae Chun from Sogang University.
"The decision is very commonsensical... We hope the conservatives (who support Park) will accept it and move forward."
South Korea will have to elect a new president by May 9. Mr Moon Jae In, former chairman of the main opposition Democratic Party, is the front runner in opinion polls.
Supporters of Ms Park's impeachment gathered in central Seoul last night to celebrate her ouster. Businessman James Kim, 43, said: "I totally agree with the court's decision. I'm ashamed of corrupt politicians who supported Park and companies like Samsung that gave bribes. It is time to clean up the system."