Originally a four-member group composed of Yoon Min-soo, Jeong Se-young, Han Hyeon-hee and Lee Jeong-ho, 4Men released their debut album Four Men First Album on February 1, 1998.

Two years later, they released their second album Ireoke Cheonildongan Moeumyeon Ibyeori Sarajindago Haetda on December 29, 2000.

In 2008, all members withdrew from the group, Jeong Se-young and Han Hyeon-hee join and form R&B group Someday in 2009, however, although, it later disbanded in 2011, later Jeong Se Young and Yoo Sung-gyu, better known as Noblesse, join and form the r&b duo, Takeout.

[1] On August 31, 2019, it was announced that Shin Yong Jae and Kim Won Joo had departed from MAJOR9 after their exclusive contracts expired and formed vocal duo, 2F.

The following day, MAJOR9 confirmed that the group would have a new, 4th generation lineup for the comeback, consist of Haeun, Joseph, and Hanbin.