The lurch back to South Korea's dark days of military rule on December 3 only lasted a few hours, and after a night of protests and high drama Yoon was forced into a U-turn by lawmakers.
He has since been impeached -- pending a court trial that began this week -- and resisted arrest until Wednesday, when he backed down to investigators after a tense, weeks-long political standoff.
He said the investigators did not have the authority to arrest him and that he had only complied to avert "bloodshed" -- but his name is now etched in history.
As well as the first sitting South Korean president to be arrested, he is the third to be impeached by parliamentary vote, and, if upheld by the Constitutional Court, would be the second to be removed from office.
- Born in dictatorship -
Born in Seoul in 1960 months before a military coup, Yoon studied law and went on to become a public prosecutor and anti-corruption crusader.
He played an instrumental role in Park Geun-hye, South Korea's first female president, being impeached in 2016 and later convicted for abuse of power and imprisoned.
As the country's top prosecutor in 2019, he also indicted a senior aide of Park's successor, Moon Jae-in, in a fraud and bribery case.
The conservative People Power Party (PPP), in opposition at the time, liked what they saw and convinced Yoon to become their presidential candidate.
He won in March 2022, beating Lee Jae-myung of the Democratic Party, but by the narrowest margin in South Korean history.
- Halloween to handbag -
Yoon was never much loved by the public, especially by women -- he vowed on the campaign trail to abolish the ministry of gender equality -- and scandals have come thick and fast.
This included his administration's handling of a 2022 crowd crush during Halloween festivities that killed more than 150 people.
Voters have also blamed Yoon's administration for food inflation, a lagging economy and increasing constraints on freedom of speech.
He was accused of abusing presidential vetoes, notably to strike down a bill paving the way for a special investigation into alleged stock manipulation by his wife, Kim Keon Hee.
Yoon suffered further reputational damage in 2023 when his wife was secretly filmed accepting a designer handbag worth $2,000 as a gift. Yoon insisted it would have been rude to refuse.
His mother-in-law, Choi Eun-soon, was sentenced to one year in prison for forging financial documents in a real estate deal. She was released in May 2024.
Yoon himself was the subject of a petition calling for his impeachment last year, which proved so popular the parliamentary website hosting it experienced delays and crashes.
- 'You can sing' -
As president, Yoon has maintained a tough stance against nuclear-armed North Korea and bolstered ties with Seoul's traditional ally, the United States.
In 2023, he sang Don McLean's "American Pie" at the White House, prompting US President Joe Biden to respond: "I had no damn idea you could sing."
But his efforts to restore ties with South Korea's former colonial ruler, Japan, did not sit well with many at home.
Yoon has been a lame duck president since the opposition Democratic Party won a majority in parliamentary elections in April last year. They recently slashed Yoon's budget.
In his televised address declaring martial law, Yoon railed against "anti-state elements plundering people's freedom and happiness", and his office has subsequently cast his imposition of martial law as a bid to break through legislative gridlock.
But to use his political difficulties as justification for imposing martial law for the first time in South Korea since the 1980s was absurd, an analyst said.
"Yoon invoked Article 77 of the South Korean constitution, which allows for proclaiming martial law but is reserved for 'time of war, armed conflict or similar national emergency', none of which appears evident," Bruce Klingner, a senior research fellow at the Heritage Foundation, told AFP.
"Yoon's action is a damning reversal to decades of South Korean efforts to put its authoritarian past behind it," he said.
© Agence France-Presse
