2017 South Korean presidential election

An early presidential election was held in South Korea on 9 May 2017. The elections were conducted in a single round, on a first-past-the-post basis. Originally scheduled for 20 December 2017, the election was pushed forward following the impeachment and removal of Park Geun-hye on 10 March. This is due to a requirement by the constitution of South Korea for an election to be held within 60 days of a permanent presidential vacancy, which in this case was caused by the 10 March decision of the Constitutional Court of Korea to uphold the impeachment and remove Park from office. Later, it was confirmed by the government that the date of the election would be 9 May, making them the first snap presidential elections held directly. Following procedures set out in the Constitution of South Korea, Prime Minister Hwang Kyo-ahn succeeded Park as the acting president. After Park was removed from office by the Constitutional Court's ruling, acting president Hwang announced he would not run for a term in his own right.

Opinion polling before April consistently placed the Democratic Party's candidate, Moon Jae-in, runner-up in the 2012 election, as the front-runner. Second place in the opinion polls was initially held by former UN Secretary-General Ban Ki-moon, who declined to run in February, followed by Ahn Hee-jung, whilst he lost the Democratic primaries to Moon. Support for People Party founder Ahn Cheol-soo then surged, threatening Moon's lead in the polls throughout early April, before descending to approximately equal that of Liberty Korea Party's candidate, Hong Jun-pyo, in final polls.

Moon won the election with 41 percent of the vote, defeating his nearest opponent, Hong, by a nearly 2-to-1 margin. Under the Constitution of South Korea, if a president dies, resigns, or is removed by impeachment, a new election must take place within 60 days. As a result, unlike previous presidential elections, president-elect Moon took office immediately upon the confirmation of the result by the National Election Commission, with the inauguration at the National Assembly on the same day.