The so-called New Reform Party officially launched on Saturday with former People Power Party (PPP) chief Lee Jun-seok at its helm.
The new party held its founding convention at the National Assembly Members' Office Building in Seoul, where it named Lee - the chairperson of the party's platform and policy committee - its first chief.
Lee said he plans to take the path of social reform through the upcoming April general elections, and that reform is a battle with those who resist any type of change.
The party also filled in several other major posts, including naming former conservative lawmaker Kim Yong-nam as its policy committee chief.
A host of other third-party figures attended the convention, where they stressed the need for a big-tent "third zone" that included the New Reform Party. The new party has expressed its willingness to form coalitions.
In a congratulatory address at the event, former Prime Minister Lee Nak-yon, who recently exited from the Democratic Party to found the New Future Party, called on third parties to cooperate to accomplish the "tasks of the age," urging them to "work together."