South Korea's parliament has voted to strip the president of her power.
Park Geun-Hye's approval ratings have slumped in recent years.
She is being impeached over her association with a friend, who is accused of extortion which has prompted millions of people to protest in recent weeks.
It is expected that prime minister Hwang Kyo-ahn would assume leadership until the Constitutional Court rules on whether Ms Park must permanently step down.
The court has up to 180 days to decide, and the country will need to hold a presidential election within 60 days.
State prosecutors have accused her of colluding with a confidante who extorted companies and manipulated state affairs. Ms Park denies the claims.
South Korean legislators last voted to impeach a president in 2004, accusing the late Roh Moo-hyun of election law violations and incompetence. The court reinstated him about two months later.
Legislators from both parties faced huge pressure to act against Ms Park, the daughter of a military dictator still revered by many conservatives for lifting the country from poverty in the 1960s and 1970s.
As legislators arrived at parliament, hundreds of protesters, some of whom had spent the night on the streets after travelling from other cities, rallied in front of the National Assembly's main gate.
A group of anti-Park farmers who tried to roll into the capital on tractors and trucks scuffled with police overnight in Suwon, just south of Seoul, before they left most of the vehicles and headed to Seoul on buses.
Once called the "Queen of Elections" for her ability to pull off wins for her party, Ms Park has been surrounded in the presidential Blue House in recent weeks by millions of South Koreans furious over what prosecutors say was collusion with a long-time friend to extort money from companies and to give that confidante extraordinary sway over government decisions.
Her approval ratings have plunged to 4%, the lowest among South Korean leaders since democracy came in the late 1980s, and even elderly conservatives who once made up her political base have distanced themselves from her.
Ms Park's confidante, Choi Soon-sil, and two former presidential aides allegedly linked to the scandal have been indicted. The president, who has immunity from prosecution while in office, has refused to meet prosecutors investigating the scandal.
The president has publicly apologised over the scandal three times and acknowledged that she received help from Choi in editing her speeches and with unspecified "public relations" matters, but she denies involvement in Choi's alleged criminal activities.
Ms Park's father, Park Chung-hee, ruled the country for 18 years until his 1979 assassination. Choi is a daughter of Choi Tae-min, a purported cult leader who served as a mentor for Ms Park until his death in 1994.
The president, whose mother was assassinated in 1974, described Choi Soon-sil as someone "who helped me when I had difficulties" in the past.
Ms Park, whose term is to end in early 2018, tried to fend off impeachment by saying she would stand down if parliament arranges a stable power transfer. Her liberal opponents called the overture a stalling tactic to buy time and find ways to survive the scandal.