Born on 19 February 2001 in Incheon, Kang-in-Lee began his career at the age of eight with his hometown club, Incheon United FC. He then joined Flyings FC for a year, before leaving South Korea for Spain, where he signed for Valencia in 2011. The versatile winger stayed with the Murcièlagos for ten years, progressing from the reserve team to the first team, with whom he even took part in the UEFA Champions League in 2019. That same year, he also won the Copa del Rey with his parent club. After arriving at Mallorca as a free agent in the 2021 summer transfer window, the Korean international made meteoric progress over the next two seasons and finished the 2022/2023 campaign with six goals and seven assists. As a result, Paris Saint-Germain spotted him and made a move in the 2023 summer transfer window.