Lee Jae-in is one of the few South Korean celebrities born in Gangwon, a border province with North Korea.

[2] Lee debuted in 2012 as the child counterpart of a supporting character in Ice Adonis.

Her portrayal of two different twin girls has earned her various wins and nominations from major film awards.

[4][5] In that year Lee also played her first regular role in television series with Beautiful World.

[6] In 2021 Lee was cast in JTBC's legal espionage series Undercover[7] and SBS' sport drama Racket Boys as a national youth badminton team's ace athlete.