South Korea’s ruling Democratic Party secured most of the local government seats up for election on June 3, 2026, in the first nationwide political test of President Lee Jae-myung’s administration since he took power earlier this year. The results gave the party a broad mandate in provincial and city elections across the country, though opposition candidate Oh Se-hoon won re-election as mayor of Seoul, protecting one of the most symbolically important local offices from a Democratic sweep.

The elections covered mayors, governors, and council seats across all of South Korea’s 17 regional administrative units. Analysts and party strategists on both sides had framed them as a referendum on Lee’s early governance, which has been marked by an ambitious domestic agenda and a shift in South Korea’s diplomatic stance toward China and away from the hardline approach of his predecessor.

The Seoul mayoral race drew the heaviest attention. Oh Se-hoon, the conservative People Power Party incumbent, beat his Democratic challenger by a margin of roughly four percentage points, extending his hold on the country’s capital and its 10 million residents. The Seoul mayorship is widely viewed as a launching pad toward a future presidential campaign, making Oh’s survival an important result for the opposition.

The June 3 elections also included 14 National Assembly by-elections in constituencies where seats had fallen vacant, making them the largest by-election set since South Korea’s democratisation in the late 1980s. The Democratic Party won nine of the fourteen seats, reinforcing its majority in the National Assembly and giving Lee greater legislative room to push through his policy agenda.

Former President Yoon Suk-yeol, who had been convicted earlier this year on charges related to a short-lived martial law declaration in December 2024, was sentenced in June to an additional 30 years in prison over a separate plot involving North Korean drones. Yoon’s ongoing legal troubles have weakened the People Power Party’s credibility in the wider electorate, a dynamic that likely contributed to its losses in the June 3 contests outside Seoul.

Voter turnout in the local elections reached 52 percent, higher than most recent midterm cycles and a sign of elevated public engagement in a year of significant political transition. Lee, addressing supporters after the results were confirmed, said the outcome reflected public trust in his government’s direction and called for continued cooperation from the opposition-controlled Seoul city government.

South Korea’s political landscape remains divided despite the Democratic victory. The opposition still controls the Seoul mayor’s office and several key provincial governorships, and the People Power Party has vowed to regroup ahead of the 2028 presidential contest. Relations between Seoul and the new government in Pyongyang, where Kim Jong Un’s daughter has taken on a more prominent role, also remain a key foreign policy issue the Lee administration will need to navigate. Official election results are maintained by the National Election Commission of Korea.