Secret Garden, the first group of Boo Entertainment, has 5 members. The names were Sulhwa, Hayun, Bobin, Nanhee, and Chaeyeon. They initially debuted on October 4, 2019. However, the debut moved to October 7, 2019, due to technical problems. They released their debut song, Our Secret along with their debut album, Secret. 

​

They came back just a month later, with their song, Flower Shower, on their 1st mini-album, Bloom Like A Flower. 

​

They were also featured on the 2019 Season Greeting special song of Boo Entertainment, which is "Christmas", alongside other artists of Boo Entertainment.

​

Sulhwa, the main dancer and leader of Secret Garden joined a survival show, IDREAM30. She made it on the final episode, but unfortunately winning 14th place, marking her not debuting the former group, FAN7ASY, where Hannah also participated in the show and winning 7th place.

​

They came back in February 2020, with their new song, Heartbeat on the 2nd mini-album, In A Heartbeat. The song and the album gave a momentum of popularity around Secret Garden. This also boosts their popularity when Chaeyeon accidentally swore in the program, Audiostar.

​

There have been rumors about collaborations with other artists, such as CiCz from CiCz Entertainment, however, there is no news and the rumors are false. They also joined as a judge of the survival show in a collaboration with CiCz Entertainment, YJ Entertainment, and Boo Entertainment, called "LUCKY WWW" or Lucky W. However, the survival show was unfinished and discontinued after reports seeing as the survival show, was not getting much attraction and have been also due to the Coronavirus pandemic. They also have been rumors about Secret Garden joining Queendom on WNet, and this was actually to be proven true. However, there are still no updates on whether the show will continue or not, and it is still unlikely whether the show will start.

​

On June 22, 2020, Secret Garden announces their new project called "Chaeyeon's Crush Trilogy", which will show the infatuation of Chaeyeon and the reference to all from the Heartbeat music video. On the same day, they loaded the teasers of the "Say Hello To You!" which is the 3rd mini-album and the first part of the trilogy project. The music video of Hello, the main song of the 3rd mini-album, was posted on June 26, 2020, both Instagram and YouTube SNS.

​

On October 19, Secret Garden came back with the song, Shy Boy, on the 4th mini-album, You Are My Boy. They also upload a dance practice video of their sidetrack, Starlight Moonlight. The song receives much popularity, and it even won SBC Inkigayo's Song of the Week. It also made them participate in the Memoworld's Memo Show, with the song winning 4th place.

​

Nanhee, lead rapper and visual, joined a collaboration with Snow Kong, Seya, Joohyun (LAUVELIZE), and Nene (Bonbon Girls), to form Pente Mixes. The collaboration group debut on November 13, 2020. The collaboration has been successful and won 2 "Best Collaboration" awards. Pente Mixes disbanded on March 2021, due to the management of both companies, Fantasia and BonBon Entertainment closed down, and 2 of the members leaving the collaboration. 

​

The trilogy project,"Chaeyeon's Crush" was officially cancelled, as announced by Boo Entertainment on August 2021. They also announced that Secret Garden is also preparing a comeback to be schedule releasing on Winter 2021.

​

On early December, the company released the teaser photo of the comeback with the title, "We are gonna funk it up!", stating that the release date is on late December. However, Typhoon Rai made the company to postpone the comeback to February. However, by May, the company just said that the comeback will be postponed indefinitely, and will moved to a later date.

​

On August 12, 2022, after more than a year from their last hit comeback, they released a ballad-vocal 1st ever digital single titled, "Lead Me (My Only Butterfly)".