Until the middle of the ballot count in the June 3 local elections, Oh Se-hoon of the People Power Party, who had been trailing Chong Won-o, the Democratic Party of Korea candidate for Seoul mayor, pulled off a dramatic come-from-behind lead near the end of the count. As the count continued after the reversal, the gap widened, making Oh's victory all but certain. Chong acknowledged defeat, saying, "We solemnly and humbly accept the citizens' choice."
As of 9:37 a.m. on the 4th, with 97.7% of the ballots counted, Oh had 2,501,865 votes, leading Chong (2,471,506 votes) by more than 30,000. Oh's vote share was 48.94%, ahead of Chong (48.34%) by 0.6 percentage point (p).
In the early stage of the count, which began around 6:20 p.m. on the 3rd, Chong's share was more than 30 percentage points higher than Oh's. Even after the count surpassed 50%, the gap between the two exceeded 20 percentage points. At the time, based on exit polls by the three major broadcasters, Chong was expected to win.
That trend began to shift after 2 a.m. on the 4th as the gap narrowed. After shrinking to 5 percentage points, it tightened sharply to a 1–2 percentage point difference around 5 a.m. After 6 a.m., it narrowed to around 0.5 percentage point, and at about 7:17 a.m., a "golden cross" occurred as the two candidates' rankings flipped.
After that, the gap between the two candidates continued to widen.
On the morning of the 4th, Chong conceded defeat and congratulated Oh on the victory. Chong said, "I apologize for failing to live up to the expectations of the citizens who trusted and stayed with me, as well as the campaign staff and party members," adding, "I extend my congratulations to Oh Se-hoon on his election."
Oh was set to head to his Jongno, Seoul, campaign office soon to deliver remarks on the victory. Oh said, "This election result is the citizens' victory," adding, "I will devote all my capabilities over the final four years for Seoul."
However, regarding this Seoul mayoral election, the National Election Commission's poor management is expected to come under scrutiny. At 12 polling stations in Songpa-gu, one in Gangnam-gu, and one in Gwangjin-gu, a shortage of ballots led voters to wait or turn away.