Pre-debut project
On September 28, 2016, Blockberry Creative released a teaser for the first music video, Heejin's "ViViD". On October 2, South Korean company Blockberry Creative announced through Naver that they would be debuting their first girl-group through a 12-month long pre-debut project.Following this announcement, teasers were released for the first member, Heejin,as well as the teaser for an additional music video for the acoustic mix of "ViViD", set in Paris, France. On October 4, the music video for "ViViD" and it's accompanying acoustic mix were released.

On October 28, the second member, Hyunjin, was revealed.On November 10, Hyunjin's debut single "Around You" was released in a 10-minute short film format music video. Six days later, the music video for Heejin and Hyunjin's collaboration song "I'll Be There", filmed in Tokyo, Japan, was released, along with the official music video for "Around You".

On December 3, the third member, Haseul, was announced. On December 11, the music video teaser for "Let Me In" was released, revealing Haseul's music video to have been filmed in Iceland. On December 14, the music video teaser for Heejin, Hyunjin, and Haseul's collaboration Christmas song "The Carol" was released, and the music video was revealed to have been filmed in London, England. On December 15, the music videos for "Let Me In" and "The Carol" were released.

On January 4, 2017, the fourth member, Yeojin, was revealed. On January 12, the music video teaser for Yeojin's debut single, "Kiss Later" was released. The following days a teaser for Heejin and Hyunjin's second single, "My Sunday", and a teaser for Haseul and Yeojin's first single "My Melody" was revealed, both music videos were filmed in Taipei, Taiwan. The official music video for Yeojin's "Kiss Later" was released on January 16, followed by Heejin and Hyunjin's "My Sunday" on January 17, and finally Haseul and Yeojin's "My Melody" on January 18.

On February 13, the fifth member, Vivi, was revealed. Loona's first sub-unit, LOONA 1/3, consisting of Heejin, Hyunjin, Haseul and new member, Vivi, will release the extended play, Love&Live, and accompanying single of the same name on March 13. The sub-unit will officially begin promoting from March 12, with promotions beginning on SBS's Inkigayo

They released a repackaged edition of the album, titled Love & Evil, on April 27.Between April 2017 and July 2017, members ViVi, Kim Lip, JinSoul, and Choerry released their solo albums, continuing the same monthly pattern.The group's second sub-unit, Odd Eye Circle, consisting of JinSoul, Kim Lip and Choerry, released the extended play Mix & Match on September 21, 2017, and began promotions on Mnet's M Countdown.The English version of "Loonatic" was released on October 23.On October 31, they released a repackaged edition of the album, titled Max & Match, which included three new songs.On November 28th, 2017, they released the solo album for the ninth member Yves.

In September 2017, three members, HeeJin, HyunJin and HaSeul, auditioned for JTBC's reality show Mix Nine, only HeeJin and HyunJin passed the audition stage making it onto the show,where Heejin placed fourth in the finale.

The group's second sub-unit, Odd Eye Circle, consisting of JinSoul, Kim Lip and Choerry, released the extended play Mix & Match on September 21, 2017, and began promotions on Mnet's M Countdown.[11] The English version of "Loonatic" was released on October 23.
On October 31, they released a repackaged edition of the album, titled Max & Match, which included three new songs.

Between the months of November 2017 and January 2018, they released the solo albums for new members Yves, Chuu, and Go Won
continuing the monthly pattern. In March of 2018, they released the solo single album for final member, Olivia Hye.On May 30, 2018, the group's third sub-unit, Loona yyxy, made their debut with the extended play Beauty & the Beat. The single "Love4eva" featuring Canadian musician Grimes was released the same day with an accompanying music video.