Park Seo-ham, the KNK singer who found his audience after leaving the stage

Park Seo-ham

Photo: 오렌지디 / CC BY 3.0, via Wikimedia Commons

Born	October 28, 1993 Siheung, Gyeonggi Province, South Korea
Occupation	Singer, actor

Park Seo-ham spent five years in a K-pop group that the trade press kept calling promising, then walked away and found, in a single streaming series, the audience the band never reached. The actor viewers now know as Jang Jae-young, the design student of Semantic Error, learned his trade on music-show stages and in rehearsal rooms, and every role he plays still carries the discipline of a performer trained to be watched from every angle.

The usual version of his story says an idol gave up music for acting. It gets the order wrong. Acting came first, music was the long detour, and the songs have never entirely left.

Siheung, the Gyeonggi Province city south-west of Seoul where he was born on 28 October 1993, knew him first as Park Gyeong-bok; as a child he was renamed Park Seung-jun, the name he would debut under. Music ran in the family. His father, Park Han-seok, conducted the Siheung Wind Orchestra. The son took the trainee route instead. He trained at Big Hit Entertainment in the same years as the boys who would become BTS, and in February 2013 he placed second in JYP Entertainment’s tenth open audition, signing on as an acting trainee. Neither company gave him a debut.

That came through a much smaller label, YNB Entertainment, where he and his future bandmates first worked as backup dancers for the girl group Bestie. YNB assembled five of them as KNK, short for Keunakeun, a Korean word for “great”, and launched the group on 3 March 2016 with the single album Knock. The early run was strong for an independent act. The EP Awake, led by “Back Again”, reached No. 7 in Korea and No. 14 on Billboard’s World Albums chart, and Billboard named KNK among the most promising K-pop debuts of the first half of 2016. In 2017 the single album Gravity, with “Sun, Moon, Star”, climbed to No. 6, its reissue Gravity, Completed added “Rain”, and that October KNK made its Japanese debut with the single “U / Back Again”.

The breakthrough that those numbers suggested never quite arrived. Late in 2017 Park, Inseong and Heejun entered Mix Nine, the survival show run by JTBC and YG Entertainment; all three passed the auditions and were eliminated before the final. In 2018 the group lost Youjin, who left after being diagnosed with a panic disorder, and in September the remaining four ended their contracts with YNB, citing long-running management problems, and regrouped at 220 Entertainment. In October that year Park Seung-jun became Park Seo-ham, his third name; he explained that his family had opposed a return to the first.

The reshaped KNK, with Lee Dong-won added, kept working: Lonely Night and the summer single album KNK S/S Collection, led by “Sunset”, in 2019, tours of four American and six European cities, and in September 2020 the EP KNK Airline, whose title song “Ride” came after fans funded the project on MAKESTAR in ten minutes.

Read honestly, the KNK catalogue tells the story of a group that did most things right and still could not outgrow its scale: a small agency competing for airtime and chart space with the largest companies in the industry. Park was not the group’s songwriter either. The credits the band’s history highlights belong to Youjin, Heejun and leader Jihun. What he brought was presence, and he had already been testing it elsewhere, on the 2017 show Idol Acting Competition, in a small role in Children of the 20th Century and in the web dramas Just One Bite and One Fine Week 2. When 220 Entertainment announced on 30 September 2021 that he was leaving KNK after long discussions about his future, the decision looked less like a defection than a return to the plan JYP had signed him for eight years earlier.

The return paid off almost at once. Semantic Error, an eight-episode Watcha original directed by Kim Soo-jung from Jeo Soo-ri’s web novel, premiered in February 2022 with Park as Jang Jae-young, opposite Park Jae-chan of the group DKZ as the rule-bound computer science student Chu Sang-woo. It became the first boys’ love series to reach a mainstream Korean audience. A theatrical cut, Semantic Error: The Movie, sold out its Bucheon festival screenings in a minute, and Korean studios answered with a wave of BL productions. The two leads shared the Best Couple Award at the APAN Star Awards, and Park won a Popular Star Award at the first Blue Dragon Series Awards.

The timing was cruel. Npio Entertainment signed him on 7 March 2022, and three days later he began his mandatory military service as a social service agent, which froze the momentum at its peak. He was discharged in December 2023. Waiting for him was Jung Cheon in The Murky Stream, his first historical drama, a Disney+ series with Rowoon and Shin Ye-eun about a young man who dreams of becoming an honest official. Its first two episodes premiered at the 30th Busan International Film Festival before the series began streaming in September 2025.

Music did not disappear in the meantime. In 2025 he recorded a new version of “My Valentine” with Lee Si-woo for the soundtrack of Show Musical Dream High, the stage adaptation of the 2011 drama about an arts high school for future idols; Nichkhun and Taecyeon of 2PM sang the original. It is a small credit, and a fitting one: a song from the idol-school fantasy that shaped his generation of trainees, sung by someone who lived the less glamorous version.

This has been his busiest year on screen. In tvN’s Our Universe, broadcast from February to March, he played Park Yoon-seong, the third point of a love triangle with Roh Jeong-eui and Bae In-hyuk. After a summer cameo in See You at Work Tomorrow!, since 26 September he has co-led Dive into You on Channel A, a fantasy romance co-produced by Korea’s Dexter Pictures and Japan’s Amuse, with Rakuten Viki carrying it worldwide. He plays Jung Woo-jae, a bodyguard who dies protecting the star played by Kim Ji-yeon; the plot turns on her attempt to go back in time with an old camcorder and save him. Domestic ratings have been small, 0.3 and 0.5 per cent for the first two episodes, yet the series ranked seventh in Good Data Corporation’s combined TV and streaming drama buzz chart in its opening week. That gap between broadcast numbers and online attention has followed Park since Semantic Error.

The next stage is a literal one. On 14 November he holds his first solo fan meeting in Japan, subtitled Prologue, at Hulic Hall Tokyo, nine years after KNK made its overseas debut in the same country. The format belongs to neither of his careers alone, which may be why it suits him: for one evening, the singer and the actor answer to the same microphone.

Tags: singers, K-pop, Dive into You, Park Seo-ham, KNK, Park Jae-chan