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Sejeong (세정) is a South Korean singer-songwriter and actress under Jellyfish Entertainment. She is a former member of the girl group gugudan, its sub-unit SEMINA, and the project group I.O.I.

She made her solo debut on November 23, 2016 with the digital single "Jelly Box Flower Way".


2012: K-Pop Star 2

In 2012, at the age of 16, Sejeong became a contestant on the competition show K-Pop Star 2. She was eliminated in the second round, but was brought back by Yang Hyun Suk as a wild card. Ultimately, she was once again eliminated in the final casting round.[2][3]

2016: Produce 101, I.O.I, debut with gugudan, solo debut

In January 2016, Sejeong became a contestant on the survival show Produce 101, where she would represent Jellyfish Entertainment. She ranked 2nd in the finale, thus becoming a member of I.O.I.[4] The group officially debuted on May 4 with their first mini album Chrysalis.

On June 23, Sejeong was revealed as the fifth member of gugudan.[5] The group officially debuted on June 28 with their first mini album Act.1 The Little Mermaid. As a result, Sejeong was absent from the promotions of I.O.I's single album "Whatta Man".

On November 23, as part of Jellyfish Entertainment's music channel project Jelly Box, Sejeong made her solo debut with the digital single "Jelly Box Flower Way".

2017: I.O.I's disbandment, acting debut

On January 29, 2017, I.O.I officially disbanded following the release of their third and final digital single "Downpour".

In July, Sejeong made her acting debut through KBS2's teen drama School 2017, in which she played the female lead role.[6]

2018–2021: Debut with gugudan SEMINA, gugudan's disbandment

On July 10, 2018, she debuted as a member of gugudan's second sub-unit, gugudan SEMINA, with their first and only single album "Semina".

On December 30, 2020, Jellyfish Entertainment announced gugudan would disband on December 31 after four years together.[7]

On May 11, 2021, Jellyfish announced that Sejeong had renewed her exclusive contract with the agency.[8]

Personal life


She is currently attending Hanyang Women's University.[citation needed]


Mini albums

Digital singles



Producing & writing credits

  • All credits adapted from KOMCA, unless stated.[9]
Artist Song Album Type
Gugudan "Dear (너에게)" Act.5 New Action Writing
Herself "Hopes For Tomorrow" Plant Writing, composing
"Swim Away (오리발)"
"In My Dream (꿈속에서 널)" Writing, composing, arranging
"Whale" "Whale" Writing, composing
"Meet Again" The Uncanny Counter OST Part.2 Writing, composing, arranging
Herself "Teddy Bear" I'm Writing, composing
"Do Dum Chit"
"Let's Go Home (집에 가자)"
"Maybe I Am (아마 난 그대를)"



  • The Sound Of Your Heart (KBS2, 2016)
  • School 2017 (KBS2, 2017)
  • I Wanna Hear Your Song (KBS2, 2019)
  • The Uncanny Counter (OCN, 2020-2021)
  • A Business Proposal (SBS, 2022)
  • Today's Webtoon (SBS, 2022)

Reality shows

  • K-Pop Star 2 (SBS, 2012) - contestant
  • Produce 101 (Mnet, 2016) - contestant

Variety shows

  • Get It Beauty (OnStyle, 2017) - MC
  • Busted! (Netflix, 2018–2019)


  • She represents the number 3 within her group, gugudan.
  • During the course of Produce 101, she got the nickname "God Sejong" because she remained in first and second places and never going lower than that.
  • Prior to Produce 101, she trained for 1 year and 7 months.[10]
  • She was a part of the all-female non-professional soccer club called 'FC Rumor W', along with other idols, such as her fellow member Nayoung, Hayoung of Apink, Jeonghwa of EXID, Mina and Jihyo of TWICE and U.Ji (former of BESTie), and also non-celebrities.[11] On August 11, 2020, it was announced by Hayoung that she and other idols, including Sejeong, decided to leave the team after the controversy surrounding it became too big.[12]


Main article: Sejeong/Gallery


Official links