Former prime minister Han Duck-soo assumed the role of acting president pending the Constitutional Court's decision on whether to remove Yoon from office.

The declaration of martial law hardened these views, with many surveyed in South Korea believing Yoon should resign voluntarily or that he should be formally removed from office.

[12] On 28 November, 1,466 South Korean Catholic priests also called for Yoon to be impeached, issuing a statement titled "How could a person be like this" (어째서 사람이 이 모양인가), which claimed that he is a puppet of private interests who has no idea what he does or who he is and who had handed over the authority entrusted to him by the people to his wife.

[15] Following an emergency meeting of the PPP, its leader, Han Dong-hoon, initially announced the party's unanimous opposition to the impeachment efforts.

[26] Prior to the impeachment vote, a motion was discussed on whether to launch a special counsel investigation on Yoon's wife Kim Keon-hee but ultimately failed due to opposition by the PPP.

[41] On 8 December, former Defense Minister Kim Yong-hyun was arrested by prosecutors on suspicion of committing insurrection by advising President Yoon to declare martial law and sending troops into the National Assembly to seize the legislature.

[42][43] That same day, Han Dong-hoon said that the PPP had "effectively obtained (Yoon's) promise to step down" in exchange for the party blocking his impeachment.

[44] A PPP special task force proposed that Yoon leave office in February or March 2025 and called for a snap presidential election to be held in April or May.

[45] On 10 December, the National Assembly passed a bill creating a permanent special counsel to investigate Yoon on charges of treason relating to his martial law declaration.

[57] As votes were counted, protesters sang "March for the Beloved", an anthem commemorating those killed during the Gwangju Uprising, and "Into the New World" by Girls' Generation, which was also used during the impeachment of Park Geun-hye.

[64] On 16 December, PPP leader Han Dong-hoon also resigned, acknowledging that Yoon's impeachment was "painful" while stating that he did not regret supporting it.

[65] The DPK said that the motion's success was "a historic victory for democracy" and pledged to continue investigating Yoon for declaring martial law.

[67] On 20 December, both the PPP and the DPK agreed to a proposal by Speaker Woo Won-shik creating a joint consultative body to discuss issues regarding national security and the economy.

[80] On 31 December, acting president Choi Sang-mok appointed Chung Kyesun and Cho Hanchang to the Constitutional Court as part of efforts to fill up the vacancies.

[94] Yoon's defense team comprised Bae Bo-yoon, a former Constitutional Court scholar and spokesperson during the impeachment trial of former president Park Geun-hye; Yun Gap-geun, former head of the Daegu High Prosecutors' Office; Bae Jin-han, a former judge and Yoon's classmate at Seoul National University School of Law; and Kim Hong-il, former head of the Korea Communications Commission.

[96] During the 3 January hearing, Yoon's defense team defended the declaration of martial law as a "national emergency situation" and said that its brief duration "did not restrict the people's basic rights".

[102] On 13 January, Yoon's lawyers requested the exclusion of Justice Chung Kyesun from hearing the case, accusing her of progressive leanings and showing her "prediction" for the trials during her confirmation by the National Assembly in December 2024.

It also called for additional witnesses, including former defense minister Kim Yong-hyun and police commissioner Cho Ji-ho, to testify.

Yoon stated that the soldiers deployed to the legislature were not intended to suspend the National Assembly or obstruct its efforts to lift martial law, acknowledging that such actions would have caused a crisis.

[111] Kim denied allegations that Yoon had ordered the military to storm the National Assembly to prevent lawmakers from convening and passing a resolution nullifying martial law.

The team alluded to Moon's past social media interactions with DPK leader Lee Jae-myung, Justice Lee's brother, who serves as a vice chairman of a committee at the Lawyers for a Democratic Society and had supported Yoon's resignation, as well as Justice Chung's husband, who had signed a public declaration supporting Yoon's impeachment.

[115] Appearing again for the 4 February hearing, Yoon admitted to ordering soldiers to the NEC to check its systems operations, citing allegations of election fraud.

[119] At 13 February hearing, which Yoon attended,[120] former NIS first deputy director Hong Jang-won, who previously testified to compiling a list of politicians as instructed by Yoon to "clean them all up" during martial law, revealed that he had been contacted through text messages by first lady Kim Keon-hee on the night of martial law, but could not recall the exact details.

His statement was disputed by NIS director Cho Tae-yong, who cited multiple discrepancies and accused Hong of links with opposition politicians.

A petition filed at the National Assembly website calling for the PPP's dissolution garnered more than 171,000 signatures,[129] exceeding the 50,000 needed to have the proposal submitted to the relevant standing committee.

[132] Trains running on Line 9 of the Seoul Metropolitan Subway avoided stopping at the National Assembly station to prevent congestion-related accidents.

[133] Yoon's supporters have rallied around slogans such as Make America Great Again and Stop the Steal inspired by U.S. President Donald Trump.

[134] The Korea Times drew comparisons between Yoon's impeachment and that of President Park Geun-hye in 2017, suggesting Yoon survived the first impeachment attempt due to PPP fears that it would suffer a crushing defeat in any ensuing snap presidential election, similar to what happened to the Saenuri Party seven years earlier after Park was removed from the presidency.

[135] Multiple opinion polls have shown DPK and opposition leader Lee Jae-myung maintaining a strong lead in any prospective matchup since early 2024, with the margin widening further following the martial law declaration.

[138] The same poll also found Speaker Woo Won-shik emerging as the most trusted politician in South Korea for his actions during martial law and the impeachment, with a rating of 56%.