[4] At the age of five, Jaehyun moved to Connecticut, USA with his parents, where he went by the English name Jay Jeong.
[6][7] Jaehyun returned to South Korea at the age of ten, and said that he struggled adapting back to Korean culture.
[8] He later became interested in music at a young age due to his parents' influence; he learned to play the guitar and the piano, and eventually began singing during his middle school.
[14] In December 2015, Jaehyun performed "A Whole New World" on Disney Channel Korea's The Mickey Mouse Club.
[19] In January 2018, Jaehyun released the single "Timeless" alongside a new NCT U lineup as part of the SM Station project.
[21] On September 4, 2020, it was confirmed that Jaehyun would make his acting debut as Cha Min-ho – a second-year computer science student at Seoyeon University, in the KBS2 drama Dear.
[22] The airing of the drama was postponed indefinitely after lead actress Park Hye-su was accused of school bullying.
On November 2, 2021, Jaehyun was confirmed to star in a KakaoTV web series, a remake of the 2001 South Korean film Bungee Jumping of Their Own, playing the leading role of Im Hyun-bin.
[25] On December 9 of the same year, during pre-production, KakaoTV announced the cancellation of the project due to concerns regarding the LGBT plot from the original film's screenwriter.
[31] On July 3, 2023, it was announced that Jaehyun will make his feature film debut in the mystery thriller You Will Die In 6 Hours, based on the Japanese novel of the same name.
[36] The eight-track album was released on August 26, and included Korean and English versions of the title track "Smoke".
On September 7, "Smoke" achieved a first place win on South Korean music program Show!
[citation needed] On October 16, Jaehyun made his feature film debut in the mystery thriller You Will Die in 6 Hours.
Jeong Jaehyun's debut has shown incredible ticket power, making it a dark horse at the box office.
"[44] Ahead of his mandatory military service, Jaehyun released a single titled "Unconditional" on October 24, 2024,[45] and held a sold out fan concert titled "2024 Jaehyun Fan-Con
[46][47] On September 26, 2024, SM Entertainment announced that Jaehyun had started the enlistment process to carry out his mandatory military service.
[50] Following various successful collaborations with Prada, Jaehyun was selected as a global ambassador in June 2022, citing his influence and unique fashion style as a reason.
[52] Photographed by David Sims, the campaign draws "upon the characteristics of classic Hollywood and European movies - their images are frames within divergent stories, glimpses of an unseen narrative and an unknown script, a tension again between different views, of different lives" and features Jaehyun alongside actors Vincent Cassel, Louis Partridge, Hunter Schafer, and Letitia Wright and models Guinevere van Seenus and Rachel Williams.