The year he turned 20, he debuted as a member of the actor group 5urprise with the web series After School: Lucky or Not. That year he also appeared in SBS The Suspicious Housekeeper and the MBC one-act drama Haneuljae’s Murder.
The breakthrough yearThe year he turned 21, he played the younger man Gook Seung-hyun in MBC Cunning Single Lady and became known. In May he appeared in his first variety show, SBS Roommate, and in November he held a showcase for 5urprise’s first album.
In 2015, he played Hong Joo-won in MBC Splendid Politics and appeared in the film The Beauty Inside. In 2016, he played Baek In-ho in tvN Cheese in the Trap. He says the drama became the work that made his name. In November, tvN Entourage began. In 2017, he won the Best Icon award in the actor category at the Asia Artist Awards.
In 2018, he took on a dual role in KBS2 Are You Human? and played On Joon-young in JTBC The Third Charm. In 2019, he played Kim Young-goon in OCN Watcher. In 2020, he appeared in JTBC When the Weather Is Fine and moved to Man of Creation, along with Kang Tae-oh, Yoo Il and Lee Tae-hwan.
In November 2021, he entered the Army, and in December the film A Year-End Medley was released. In 2022, Disney+ Grid, filmed before his enlistment, was released during his service. He was discharged at the end of his term in May 2023.
In 2024, MBC announced that he was cast in Undercover High School. In 2025, Undercover High School aired, and in June he made a special appearance by voice in SBS Spring of Youth. In December he received his first grand prize at the MBC Drama Awards.
In 2026, Netflix Boyfriend on Demand was released, and in September KBS2 A Love Other Than Yours began.
Seo Kang-joon (born Oct 12, 1993) debuted on Sep 2, 2013, the year he turned 20, with the web series After School: Lucky or Not, and became known in 2014, the year he turned 21, as Gook Seung-hyun in MBC Cunning Single Lady. He received his first grand prize in 2025, the year he turned 32.
Ages are by calendar year (the year minus the birth year), birthdays aside.
Debuted as a member of the actor group 5urprise with Yoo Il, Gong Myung, Kang Tae-oh and Lee Tae-hwan. An article describes it as Korea’s first actor group.
Source 02 · Financial News (Korean) · 5urprise interview · opens in a new tabSource 01 · OhmyNews (Korean) · 5urprise’s first album · opens in a new tab Sept. 2 follows the Sept. 26 article, which says the show first aired on the 2nd of the month.First appeared as a newcomer, playing Choi Soo-hyuk, leader of a school band.
Source 03 · Maeil Business Newspaper (Korean) · First appearance in The Suspicious Housekeeper · opens in a new tabPlayed Yoon-ha in a one-act drama that also starred Moon So-ri. Sports Kyunghyang describes it as his first lead role.
Source 04 · Yonhap News Agency (Korean) · Haneuljae’s Murder airs · opens in a new tabSource 05 · Sports Kyunghyang (Korean) · Haneuljae’s Murder · opens in a new tabPlayed Gook Seung-hyun, a younger man, in a Wednesday-Thursday miniseries starring Joo Sang-wook and Lee Min-jung. Episode 1 drew 5.4%.
Lived in one house as one of 11 cast members. It was his first variety show.
Source 11 · Maeil Business Newspaper (Korean) · Roommate premieres · opens in a new tabSource 10 · Nocut News (Korean) · Seo Kang-joon interview · opens in a new tabPlayed Eun-ho in the weekend drama. The Sept. 14 episode drew 27.5%, the highest since the premiere.
Source 12 · Ajunews (Korean) · What Happens to My Family? ratings · opens in a new tabThe five members held a showcase marking the release of their first album. After working separately following their debut, they resumed group activity after about a year.
Source 01 · OhmyNews (Korean) · 5urprise’s first album · opens in a new tabSource 13 · Newsway (Korean) · 5urprise showcase · opens in a new tabSource 14 · TV Daily (Korean) · 5urprise showcase · opens in a new tabAppeared in the Monday-Tuesday drama as the adult Hong Joo-won, from episode 7.
Source 15 · Sports Kyunghyang (Korean) · Splendid Politics, Seo Kang-joon’s first appearance · opens in a new tabSource 16 · TenAsia (Korean) · Splendid Politics, Hong Joo-won · opens in a new tabAppeared in a film in which 21 actors played the lead role of Woo-jin. The film opened in August and drew 2,051,525 admissions.
Source 17 · Sports Donga (Korean) · Chinese version of The Beauty Inside · opens in a new tabSource 18 · TV Report (Korean) · Busan International Film Festival news · opens in a new tab The month of release is confirmed in news reports, but the day is not.Played Baek In-ho in the Monday-Tuesday drama. In an April MBN interview he says this work became the one that made his name.
Source 19 · News1 (Korean) · Cheese in the Trap, Seo Kang-joon · opens in a new tabSource 20 · MBN (Korean) · Seo Kang-joon interview · opens in a new tabPlayed Cha Young-bin in a Friday-Saturday remake of an American drama. Episode 1 averaged 2.5%.
Source 21 · Seoul Economic Daily (Korean) · Entourage premieres · opens in a new tabSource 22 · Yonhap News Agency (Korean) · Entourage first-episode ratings · opens in a new tabWon the Best Icon award in the actor category at a ceremony held at Jamsil Indoor Stadium.
Source 23 · News1 (Korean) · 2017 AAA Best Icon award · opens in a new tabSource 24 · Sports Chosun (Korean) · 5urprise at the AAA · opens in a new tabTook on a dual role in his first lead role on a terrestrial network. Episode 1 drew 5.2%.
Source 25 · Yonhap News Agency (Korean) · Are You Human? first-episode ratings · opens in a new tabPlayed On Joon-young in a Friday-Saturday drama about a 12-year romance with Esom.
Source 26 · Korea Economic Daily (Korean) · The Third Charm · opens in a new tabSource 27 · OSEN (Korean) · The Third Charm · opens in a new tabPlayed Kim Young-goon, a member of an anti-corruption investigation team, alongside Han Suk-kyu and Kim Hyun-joo.
Source 29 · Star News (Korean) · Watcher teamwork · opens in a new tabSource 28 · Sports Chosun (Korean) · OCN genre dramas · opens in a new tabPlayed Im Eun-seob, who runs a bookstore with Park Min-young. Episode 1 drew 1.925%.
Source 30 · Yonhap News Agency (Korean) · When the Weather Is Fine, first episode · opens in a new tabSource 31 · Nocut News (Korean) · When the Weather Is Fine premieres · opens in a new tabSigned exclusive contracts with a new agency along with Kang Tae-oh, Yoo Il and Lee Tae-hwan.
Source 32 · Newsen (Korean) · Man of Creation exclusive contracts · opens in a new tabEntered a training center and then served as an active-duty soldier. He was a driver.
Source 33 · Sports Chosun (Korean) · Entering active-duty service · opens in a new tabSource 34 · JTBC (Korean) · Seo Kang-joon’s discharge · opens in a new tabAppeared in a romance film with 14 stories. It opened in theaters and on TVING on the same day.
Source 35 · News1 (Korean) · A Year-End Medley · opens in a new tabSource 36 · Newsen (Korean) · A Year-End Medley · opens in a new tabPlayed Kim Sae-ha in a Disney+ original series. The series, filmed before his enlistment, was released during his military service.
Source 37 · Xports News (Korean) · Grid ends · opens in a new tabSource 38 · Maeil Business Newspaper (Korean) · Grid final episode · opens in a new tabSource 39 · Joseilbo (Korean) · Seo Kang-joon discharged · opens in a new tabFinished 18 months of service and was discharged.
Source 40 · FT Sports (Korean) · Seo Kang-joon’s discharge · opens in a new tabSource 39 · Joseilbo (Korean) · Seo Kang-joon discharged · opens in a new tabMBC announced that he would lead a Friday-Saturday drama as his first work after discharge. It was his first MBC drama in 10 years, since Splendid Politics.
Source 41 · Ilgan Sports (Korean) · Undercover High School confirmed · opens in a new tabPlayed Jeong Hae-seong, a National Intelligence Service agent who goes undercover as a high school student. Episode 1 drew 5.6% and the final episode 12 drew 5.8%.
Source 42 · TenAsia (Korean) · Friday-Saturday drama ratings · opens in a new tabSource 43 · Newsis (Korean) · Crushology 101 ratings · opens in a new tabSource 41 · Ilgan Sports (Korean) · Undercover High School confirmed · opens in a new tabMade a special appearance by voice to support Kim Seon-min, a junior at his agency.
Source 44 · Sports Kyunghyang (Korean) · Seo Kang-joon in Spring of Youth · opens in a new tabSource 45 · The Ssen News (Korean) · Spring of Youth, episode 9 · opens in a new tab The air date follows the preview in a pre-broadcast article.Received his first grand prize at a drama awards ceremony, for Undercover High School. It was the first work he made after leaving the military.
Source 46 · News1 (Korean) · 2025 MBC Drama Awards · opens in a new tabSource 47 · MBC News (Korean) · Seo Kang-joon’s first grand prize · opens in a new tabAppeared as Seo Eun-ho. Three days after release, the series ranked fourth on Netflix’s global Top 10 non-English TV list.
Source 48 · News1 (Korean) · Boyfriend on Demand, Seo Kang-joon · opens in a new tabSource 49 · OSEN (Korean) · Boyfriend on Demand review · opens in a new tabPlayed Namgoong Ho, a partner of 10 years to Ahn Eun-jin, in a 14-episode weekend miniseries.
Source 50 · The Fact (Korean) · A Love Other Than Yours · opens in a new tabSource 51 · The Fact (Korean) · A Love Other Than Yours stills · opens in a new tabEND OF SELECTED RECORDSSelected records, 2013–2026 · not a complete list of work. “Key moment” is an editorial label, not a measure of success.
What did they do, and at what age?
AgeTrail lines up the key moments of a life by age.
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Film & TV · South Korea
Oct 12, 1993 —
Ages are counted from the birth year 1993: the year of the event minus 1993, birthdays aside. “Key moment” labels and the connecting story are AgeTrail's editorial reading.
Fact-checked: 2026.10.03 · An independent archive, not affiliated with the person or their agency.