Her ouster followed months of political paralysis and turmoil over a corruption scandal that also landed the head of the Samsung conglomerate in jail and facing trial.
The court said she had broken the law by allowing Ms Choi to meddle in state affairs, and had breached guidelines on official secrets by leaking numerous documents. She first moved in at the age of 9 and left it almost two decades later after her mother and father were assassinated.
The New York Times describes the removal of Park as part of the backlash against the old order once represented by her father, who ruled as a dictator from 1961 until his assassination in1979.
Despite the ruling, she remains inside the presidential compound. Park has apologized for putting trust in her friend, Choi Soon-sil, but denies any legal wrongdoing.
Park’s lawyer, Seo Seok-gu, who previously had 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”.
Her aides and observers said Park might need some time to cope with the sudden deprivation of the presidential prerogatives, an impending prosecutorial probe and trenchant public criticism. The country’s prime minister – a Park appointee – will continue to serve as acting president.
The court sided with lawmakers who impeached Park in December over allegations of corruption and influence-peddling.
South Korea now has two months to hold snap elections.
The ruling also stripped her of presidential immunity to criminal indictment.
According to a survey conducted jointly by Realmeter upon the request of the daily Maeil Business and broadcaster MBN, 86 percent of 1,008 respondents said that the court’s decision was “right” while 12 percent viewed it as “wrong”.
Park was born in 1952 as the first child of Park Chung-hee.
Liberal candidate, Moon Jae-in, is leading the opinion polls.
The political crisis has come at a time when rival North Korea is pushing ahead with its missile program and tension is brewing with China over a USA missile-defense system being deployed in South Korea.
Beijing has vigorously protested against the deployment, fearing its radar could see into its missile deployments.
The rather swift downfall of South Korea’s first female president is complete.
The prosecution’s special investigation unit will look into whether Lee permitted the donations with the intent to induce Park’s support – or pressure the government – for a controversial merger previous year between two affiliates, Samsung C&T and Cheil Industries.