[6][7] Jaemin became a trainee under SM Entertainment in 2013,[8] at the age of 13, after being street-cast by staff while handing out posters and collecting trash as a volunteer with his mother at an event.

[12] On July 9, he with fellow rookies were also announced as a "Mouseketeers" on the Korean revival of The Mickey Mouse Club, which would be aired on Disney Channel Korea.

[26][27] On March 13, 2019, Jaemin, alongside fellow NCT Dream members Jeno and Jisung, represented K-pop stars at the "K-Wave & Halal Show" in Malaysia.

[28] In April, Jaemin made his acting debut as the role of Han Dae-gang, the male lead character in JTBC's short web-drama Method to Hate You, based on a popular webtoon of the same name.

In October 2021, Jaemin appeared on the cover of WWD Korea magazine's Special Edition No.02, released in collaboration with Tom Ford and photographer Adam Katz Sinding.

[33] In March 2019, Jaemin attended UNICEF Korea committee's event "For Every Child" as a youth representative, meeting with Queen Mathilde of Belgium and former President of International Criminal Court Song Sang-hyun.

[34][35] In May of the same year, Jaemin, along with fellow NCT Dream member Jeno, visited children living in slums in Indonesia with South Korea-based non-governmental organization Good Neighbors.