[3] Following three years of training, Kim debuted under the mononym Sori as one-half of the duo CocoSori with the single "Dark Circle" on January 4, 2016.

[11] Alongside former Real Girls Project groupmates Heo Young-joo, Lee Ye-eun, and Yukika Teramoto, Sori competed as one of Mol Entertainment's four representatives in JTBC's reality television competition Mix Nine, during which she became the subject of controversy following a comment made by the judge Yang Hyun-suk regarding her age and the state of her career.

[13] Sori ultimately finished in seventh place in a field of ninety-seven female contestants and therefore became a member of the resulting girl group during the final episode on January 26, 2018.

[18] Sori's debut single titled "Touch", featuring the rapper Basick, was released on September 4, 2018, in conjunction with the premiere of its music video.

[20] "Touch" was performed for the first time during its showcase held at the Dongja Art Hall in Seoul, South Korea on the day of its release.

[21] The single enjoyed minor commercial success, where its physical version debuted and peaked at number 49 on the Gaon Album Chart.

[28] Promotions for the single were held the following month due to the holiday season, which included a collaborative performance with the internet personality StarTy in Hongdae, Seoul.

[30] The fanmeet was presented by the singer Miho Miyazaki,[31] while choreographers MikuNana and former Real Girls Project groupmate Lee Su-ji appeared as guests.

[45] She subsequently performed at the series' joint concert titled "Some Days" and "Some Nights", which was held on January 18, 2020, at the Sangmyung Art Center in Hongji-dong, Jongno District.

[46] Sori made a cameo appearance as a jazz club singer in the fourth episode of OCN's action and science fiction television series Rugal, which premiered on April 5, 2020.

[47] She portrayed a fictionalized version of herself in Naver TV's romantic drama web series Almost Famous, which was based on her personal struggles.

[48][49] Prior to the development of the series, Sori quietly retired from the music industry without informing her company and fan base and was employed as a part-time barista, but she returned shortly after online petitions emerged that encouraged her to resume her career.

[49] Sori posted a promotional photo for the single, which was revealed to be titled "Initial S", to her official Twitter account on August 20, 2020.

[55] She appeared in the final episode of TVN's fantasy and historical drama Bulgasal: Immortal Souls on February 6, 2022, during which she portrayed Min Sang-woon.