The composition of the members was created in 2014 in the show "No.Mercy", which has really welded the initially 7 guys together. But it wasn't like that since the beginning of the show. I.M joined in the course of the show, right after another participant was eliminated, which most of them didn't take well at first. So I.M had to earn the respect of the other contestants first.
On May 14, 2015, Starship Entertainment released their debut extended play "Trespass" which consists of 7 tracks. Joohoney was involved in the production of most of the tracks and he also composed several of them himself. Many of the lyrics were written by Kihyun and Wonho. 
After the 2 further EP's "Rush" and "The Clan Pt.1", the first solo concert for Monsta X followed, which was completely sold out within 5 minutes. Despite many successes and a steadily growing fanbase, Monsta X was unable to pick up an award. It wasn't until 2017 that they got their first win with the lead single "Dramarama" from the mini album "The Code". This was one of the most emotional moments in their band's history. Unfortunately, there was another very emotional event for the members, as well as the fans. On October 31, 2019, Starship Entertainment announced that Wonho was leaving the group. This is said to have been his free decision as several rumors were spread about him and he wanted to protect the other Members. 

In August 2022, all members have renewed their contracts with Starship, except for I.M, yet will continue to be a member of Monsta X, although he signed a new contract. This, of course, to the delight of the fans.