[3] When the latter enlisted in the military, he joined a practical music academy in his hometown, Mokpo, to learn more professionally,[3] working part-time to earn the necessary money.

[8] He has been writing songs and lyrics under the name Ars since 2016, starting with "Rewind" in Got7's extended play Flight Log: Departure.

Choi had a collaboration with Sanjoy and Elliott Yamin in 2017 on the song "Victim of Love",[9][10] while he recorded "I'm All Ears" with Park Ji-min for the Life Insurance Social Philanthropy Foundation's youth suicide prevention campaign in 2018.

[17] On 25 May 2020, in collaboration with Howlpot, a pet product design brand, he launched Ars X Coco, a clothing store for people and dogs, which ran for two weeks until 8 June .

[21] On 25 September 2020, he was cast in Netflix's new sitcom So Not Worth It, which tells the stories of a group of multicultural students living in a college dorm.

[33] On 20 April, he took part in Levi's 501® Day Music Concert, where he performed self-written song "Lonely", Sole's "Ride" and Christopher's "Bad".

[38] In November, he was confirmed to play his first lead role, Kim Seung-hyu, in the upcoming Cine de Rama rom-com web series Love & Wish, based on the webtoon of the same name.

[47] In October 2022, as part of a collaborative project with Esquire Korea and casual fashion brand Covernat, Choi and Yerin released the digital single "Colors".

[50] On 3 May, he was announced as part of the line-up of the 10th anniversary run of the musical The Days, in the role of Moo-young, which was played from 12 July to 3 September.

[52][53] On 3 October 2023, he was named honorary ambassador of the Korea-Thailand Mutual Visit Years by the Ministry of Culture, Sports and Tourism of South Korea.

[60] In January 2025 he was cast as Song Sam-dong in the show musical Dream High, which is scheduled to be performed in Seoul from April 5 to June 1.