On March 26, the official lineup of the group was announced; Jaekyung, Rana, Bini, Lee Sem, Eunji, Sera, Euaerin, Hyemi, and Minha. The group debuted on August 12, 2010, with the single album Let's Have a Party. They promoted the title track "No Playboy", which was produced by Rainstone and Park Jin Young. In October, Jaekyung dropped out to peruse a modeling career, and was replaced with Moon HyunA.
The group also promoted the song "Ladies" from their debut single album. Along V.O.S and ZE:A, 9MUSES performed 6 songs on Seoul Train* on December 26 to venture out into Japan.
2011: Line up change & "Figaro"
In January 2011 it was announced that the members Bini, Rana, and Euaerin would leave the group to pursue other areas, and that they will not be replaced. Euaerin left the group to pursue her dream in Japan. However, 3 months later it was announced that she would return to the group because she was not satisfied with the things she had planned.
In August, the group made their comeback with the single "Figaro" as a group of 7 members, with which Hyuna made her debut. Once the promotional period for "Figaro" started management thought to change the group name to Sweet Candy as it would confuse people if 9MUSES was a group with only 7 members. Months later the group's agency confirmed that the group name is not changing since that in the future it would add two members to become 9 girls. The group released "Figaro" and its accompanying music video on August 18, 2011.
2012: Replacements & Sweet Rendezvous
9MUSES introduced a new member, Kyungri, at the group's performance in Abu Dhabi, UAE. 9MUSES released the music video for "News" on January 10, 2012, with the single released a day later on January 11, 2012. The song was produced by Sweetune, who was also behind their "Figaro" single.
On March 6, 2012, a teaser video for "Ticket" from their Sweet Rendezvous mini album was released. The music video for "Ticket" was released on March 8, 2012. On May 25, 2012, they released two music videos for their new military campaign song "My Youth’s Allegiance"
In March 12, 2012, Star Empire announced that a new member Sungah would be joining the group. Sungah performed News and Ticket, and also Figaro in May 31, 2012.
2013: "Dolls", "Wild", and "Glue"
A single, "Dolls", was released in January 2013. It debuted at number 35 on Gaon Top 100 Chart & 11th on M!Countdown and peaked at 7th.
On May 9, 2013, the music video for the song “Wild” was released. It reached number 1 on various real-time charts and debuted on the Gaon chart at number 32, whereas the physical mini-album Wild debuted on May 16, 2013 at number On October 13, 2013, 9MUSES released their first full-length album, Prima Donna, along with its title track, "Gun".
On December 4, 2013, 9MUSES released their new digital single called "Glue" accompanied by its music video.
2014: Line up change & NASTY NASTY unit
Their agency Star Empire announced on January 29 that Lee Sem and Eunji were to leave the group. On June 23, 2014, it was announced that Sera had also left the group after her contract's expiration. On August 22, 2014, it was announced that Kyungri, ZE:A's Kevin and Star Empire trainee Sojin have teamed up to form a project unit name's "NASTY NASTY" and their song will be released on September 3 produced by composer Rado.
2015: Drama comeback, special "S/S" album and Lost
On January 8, 2015, Star Empire officially announced the group's comeback with their third mini-album, Drama, to be released on January 23. On January 12th, 2015, 2 new members were revealed. The two new girls are Jo Sojin, a member of Nasty Nasty, and Lee Keumjo, a trainee. 9MUSES hosted their Drama showcase on January 21, 2015 where they debuted their new eight member line-up and performed their title-track "Drama" for the first time. The showcase was broadcast live on YouTube.
In June 2015, 9MUSES were revealed to be preparing for a comeback. Their album will be called 9MUSES S/S Edition, where S/S stands for Special Summer. The album was digitally released on July 2, 2015, and the title track "Hurt Locker" with its MV the same day.
On November 24, 9MUSES came back once again with their fourth mini album Lost and promoted the track "Sleepless Night".
2016: 1st solo concert, Minha & Euaerin's graduation
In December 2015, Star Empire announced that the girl group would be holding their very own solo concert for the first time in February. The concert took place at Wapop Hall in Seoul Children's Grand Park on February 19. They held 2 fan meets in China.
On June 7, Star Empire announced that Minha and Euaerin’s exclusive contracts had expired and they decided to graduate from the group. It was also revealed that the group was preparing for a summer comeback with a sub-unit.
2017: Muses Diary Part.2 and Part.3
On May 31, Star Empire announced the group would comeback with a mini-album in June. It was also revealed they would be promoting without Sungah as she was focusing on individual activities. The album, Muses Diary Part.2 : Identity, was released on June 19 with "Remember" as the title track. A repackage titled Muses Diary Part.3 : Love City was released on August 3.
- Sungah (성아) - main rapper, lead dancer, vocalist (hiatus)
- Gyeongree (경리) - lead vocalist, lead dancer, visual, face of the group
- Hyemi (혜미) - main vocalist
- Sojin (소진) - main dancer, lead rapper, sub-vocalist
- Keumjo (금조) - main vocalist, sub rapper, maknae
- Jaekyung (재경) - vocalist
- Bini (비니) - vocalist
- Rana (라나) - leader, sub vocalist, rapper
- Lee Sem (이샘) - main rapper, sub vocalist
- Eunji (은지) - main dancer, lead rapper, sub vocalist
- Sera (세라) - leader, main vocalist
- Euaerin (이유애린) - main rapper, lead dancer, sub vocalist
- Minha (민하) - sub vocalist, visual
- Hyuna (현아) - leader, lead vocalist
- Prima Donna (2013)
- Sweet Rendezvous (2012)
- Wild (2013)
- Drama (2015)
- Lost (2015)
- Muses Diary Part.2 : Identity (2017)
- Muses Diary Part.3 : Love City (repackage) (2017)
- 9MUSES S/S Edition (2015)
- "Prosecutor Princess OST Part.2" (with Seo In Young) (2010)