Han verbally tendered his resignation to President Yoon Suk-yeol and all the senior presidential secretaries, including chief of staff and chief secretary for policy, offered to step down except aides in the national security office, Xinhua news agency reported.
President Yoon said he will humbly accept the will of people, shown in the elections, and will make his best efforts to reform state affairs and stabilize the economy and the people's livelihoods, according to the presidential office.
The quadrennial polls for 300 members of the National Assembly were carried out across the country on Wednesday to let voters cast ballots for 254 constituency seats and 46 proportional representation (PR) slots.
The liberal opposition bloc has won more than three-fifths of seats in the parliamentary elections, widely seen as a mid-term referendum to evaluate Yoon's management of state affairs.
The main liberal opposition Democratic Party took 161 directly contested constituency seats, while its satellite parties secured 14 PR slots.
The minor liberal Rebuilding Korea Party earned 12 PR seats, while the minor center-left New Future Party and the minor leftist Progressive Party gained one respective seat in electoral districts.
The number of parliamentary seats, snatched by the broader liberal bloc, totaled 189.
The governing conservative People Power Party and its sister party obtained 90 constituency seats and 18 PR seats each.
The minor center-right New Reform Party garnered one constituency seat and two PR seats.