2014–2015: Debut and further mini-album releases On 29 December 2014, Sonamoo officially debuted with the release of their debut EP
Deja Vu and single of the same name, and held their debut showcase performance. The album debuted at the number one spot on Gaon's weekly Album Chart. On 25 February 2015, they promoted "Just Go" as the second single off of their debut album. On 20 July 2015, Sonamoo released their second extended play
Cushion. The lead single of the same name was co-produced by EastWest and
₩uNo, who is known for being the former member of Speed, Taewoon. Members D.ana and NewSun also contributed to the writing of rap portions for two tracks: "Deep" and "Let's Make A Movie". On 1 September 2015, they followed up their
Cushion promotions by promoting "Round N Round" as the second single from the album.
2016–2021: Nahyun & Sumin's lawsuits, TS shutdown and disbandment On 29 June 2016, the group released their third extended play
I Like U Too Much, with the title track of the same name. The album presented a new side of the group with a brighter "girls next door" image compared to their debut concepts which the members themselves called "dark". The group cited they looked up to
Girls' Generation for inspiration with this album. On 9 January 2017, the group released their first single album
I Think I Love U. The lead single of the same name is a brighter dance track produced by Shin Hyuk, who has previously worked with
SHINee and
EXO. On 27 July, TS Entertainment unveiled a teaser image for Sonamoo's
Happy Box Project, revealing that the group will be releasing three singles over the course of several months. The first single "Friday Night" was released on 14 August. The rap portion of the single is written by NewSun. Member Euijin was confirmed to be a contestant on KBS Idol Rebooting Project
The Unit, which first aired on 28 October 2017. On 6 November, Sonamoo continued their
Happy Box Project releasing their single "I (Knew It)". The single is a medium tempo dance track composed by hitmaker e.one, who has previously worked with
Wonder Girls. As of 23 September 2019, both Nahyun and Sumin have filed lawsuits seeking to terminate their contract with TS Entertainment. In January 2021, Sonamoo's label, TS Entertainment, privately shut down and deleted its website, leaving the fate of the group unknown. On 9 September 2021, Euijin signed a contract with Mellow Entertainment, confirming that she had left TS Entertainment and the group. On 11 September, Minjae and NewSun also confirmed that they have left the company. On 13 September, D.ana confirmed she had also left the company. In her statement, she mentioned that Sonamoo's activities had come to an end. On 30 December, High.D confirmed that she has left the company and the group. ==Past members==