2014: Acting debut
Park Si Eun originally made her debut as a child actress in 2014 through the children's television series Pluto Secret Society.
2020: Debut with STAYC
On September 8, 2020, she was revealed as the first member of the girl group STAYC. Her prologue teaser for the group was released on October 13. The group debuted on November 12 with the single album "Star To A Young Culture".
- Love Forecast (2015)
- Golden Slumber (2018)
- Pluto Secret Society (EBS, 2014)
- Pride and Prejudice (MBC, 2014)
- Six Flying Dragons (SBS, 2015)
- Signal (tvN, 2016)
- The Good Wife (tvN, 2016)
- The Gentlemen of Wolgyesu Tailor Shop (KBS2, 2016)
- Queen for Seven Days (KBS2, 2017)
- Criminal Minds (tvN, 2017)
- Rain or Shine (JTBC, 2017)
- Still 17 (SBS, 2018)
- The Crowned Clown (tvN, 2019)
- Everything and Nothing (SBS, 2019)
- Mystic Pop-up Bar (JTBC, 2020)
- How Do You Play? (MBC, 2021) - guest (ep. 117)
- Her father, Park Nam Jung, is a famous singer from the 80s.
- Her favorite girl group is Apink.
- She is known for resembling Suzy and Park Bo-young.
- She was a trainee for 4 years.
- She joined Highup Entertainment in 2019.
- Her role model is IU.
- In the group, her designated object is rock.
- Sieun, Isa, Seeun, and J share a room in the group's dorm.
- Her MBTI personality type is ENFJ (The Protagonist).
- Her specialties are singing, playing piano, and speaking English.
- Her nicknames include Ssini and SingSingi.
- She has a pet dog named Pomi.
- Sieun sleeps a lot. Sometimes, she doesn't even hear her alarm going off.
- Her favorite movie is Titanic.
- Her dream collaboration would be with Selena Gomez or Ariana Grande.
- If she wasn't an idol, she thinks she would be a pianist or ballerina as she has been learning those two things since she was 5 years old.
- Main article: Sieun (STAYC)/Gallery