Lee was born in 2003 in Seoul. Her father, Lee Jong, competed gymnastics internationally in the 1990s and was a coach at Jeonnong Elementary School, where Lee Yun-seo and her brother began gymnastics.[2]
Junior career
Lee made her international debut at the 2017 Junior Asian Championships where she helped the South Korean team win the bronze medal behind China and Japan. She also placed fourth in the all-around and sixth on the balance beam, and she won the bronze medal on the floor exercise behind Chinese gymnasts Li Qi and Chen Yile.[3] She also competed at the 2018 Junior Asian Championships where South Korea once again won the team bronze medal behind China and Japan. Individually, she won the bronze medal in the all-around, the silver medal on the uneven bars, and the bronze medal on the floor exercise.[4]
Lee made her senior international debut at the American Cup and placed ninth in the all-around.[8] She then went to the Tokyo World Cup and finished seventh in the all-around.[9] At the Korean National Team Selection competition, she finished second in the all-around behind Kim Ju-ry.[10] She then went to the Korea Cup and won the gold medal on the uneven bars.[11] She was then selected to compete at the World Championships alongside Eom Do-hyun, Ham Mi-ju, Lee Eun-ju, and Yeo Seo-jeong, and they finished 16th in the qualification round.[12] Individually, Lee finished 28th in the all-around and was the first reserve for the all-around final.[13] This resulted earned her an individual spot for the 2020 Olympics.[14] Her final competition of the year was the Toyota International where she won the silver medal on the uneven bars behind Angelina Melnikova and the bronze medal on the balance beam behind Melnikova and Hitomi Hatakeda.[15]
2021
Lee did not compete in 2020 due to the COVID-19 pandemic. She returned to competition at the postponed 2020 Olympic Games and qualified for the all-around final where she finished 21st with a total score of 51.632.[16] She then competed at the Korean National Sports Festival and won the gold medal in the all-around, uneven bars, and balance beam, and she won the silver medal on the floor exercise behind Shin Sol-yi.[17] At the World Championships, she qualified for the all-around final in tenth place and was the first reserve for the uneven bars final.[18][19] In the all-around final, she finished 13th with a total score of 51.699.[20]
2022–2023
Lee competed at the 2022 Asian Championships in June. While there, she helped South Korea place second as a team behind China. Individually, she won bronze in the all-around, on the uneven bars, and on floor exercise.[21] She then competed with the South Korean team at the 2022 World Championships that placed 13th in the qualification round.[22] Individually, Lee qualified for the all-around final and placed 15th.[23]
Lee competed on the uneven bars at the 2023 City of Jesolo Trophy, helping South Korea win the team silver medal behind Italy. She won the bronze medal in the uneven bars final behind Italians Alice D'Amato and Giorgia Villa.[24] She also only competed on the uneven bars are the South Korean Championships, and she placed third.[25] Then at the 2023 Asian Championships, she helped South Korea win the silver medal behind China. Individually, Lee won the silver medal on the uneven bars behind China's Qiu Qiyuan.[26]
Lee placed fourth in the all-around at the Korean National Team Selection competition, leading to her selection for the 2024 Summer Olympics team alongside Eom Do-hyun, Lee Da-yeong, Yeo Seo-jeong, and Shin Sol-yi.[30] At the 2024 Summer Olympics, she finished 56th in the all-around, placing 63rd on uneven bars and balance beam, and 75th on floor exercise.[2]
^"신솔이, 여자 기계체조 대표 선발전서 1위…여서정 3위" [Shin Sol-yi takes first place in the women's artistic gymnastics national team selection competition... Yeo Seo-jeong 3rd place]. Hankyung (in Korean). 23 March 2024. Retrieved 7 June 2024.
^Hopkins, Lauren (13 February 2019). "Lee Yunseo". The Gymternet. Retrieved 11 June 2024.