More than 24.4 million of over 42.1 million eligible voters cast ballots at 13,873 polling stations to elect 300 members to the 20th National Assembly, who will serve four-year terms.
The turnout is 3.8 percentage points higher than in the previous general election in 2012, according to the National Election Commission.
The official turnout was set to be announced early Thursday.
The higher turnout is credited to record-high early voting participation and the presence of a new centrist party seen as an alternative to the long-standing two-party system.
The turnout was notably high in constituencies in Jeolla Province where two opposition parties — The Minjoo Party of Korea and People’s Party — fiercely competed.
The country saw the highest voter turnout in South Jeolla Province at 63.7 percent, followed by the administrative city of Sejong at 63.5 percent and North Jeolla Province at 62.9 percent.
Conservative bastion Daegu recorded the lowest turnout of 54.8 percent, with Busan ranking second-lowest at 55.4 percent. Seoul’s turnout was 59.8 percent, slightly higher than the nation’s average.
Early voting on Friday and Saturday, held for the first time for a parliamentary election, hit a record high of 12.2 percent. The system was first introduced for by-elections in June 2013.
More than 40 percent of South Korean voters living abroad have also cast ballots, accounting for around 3.2 percent of the total. Overseas voting took place at 198 polling booths across 113 countries.
A higher turnout is generally thought to advantage the liberal camp, which has the broad backing of young voters, while a low turnout is thought to benefit the conservative bloc.
The liberal party won big in the selection of the 17th National Assembly in 2004, when the turnout was 60.6 percent. The right-wing party had a strong showing in the next election in 2008 when the turnout was 46.1 percent.
Rain seems to have held voters at home earlier in the day. But the turnout exceeded that of the previous election by around 1 p.m. as the weather cleared up and early voting turnout was included.
When it rained in 2008 and 2012, voter turnout was among its lowest at 46.1 percent and 54.2 percent, respectively.
But the turnout was relatively higher on sunny days, with the 15th general election in 1996 recording 63.9 percent and the aforementioned 60.6 percent in 2004.
By Ock Hyun-ju (email@example.com)