Jeonbuk Hyundai Motors Lee joined
Jeonbuk Hyundai Motors in 2014 and made his debut in the
2014 AFC Champions League match against
Yokohama F. Marinos on 26 February.
Choi Kang-hee, the manager of Jeonbuk at the time, praised his ability which kept balance about attack and defense of team, and actively used him, the newcomer. In 2016, he spent his best season by providing 17 assists during a year and winning the
2016 AFC Champions League. The transfer fee paid to Jeonbuk was reported as €1.5 million. He played his first game against
Hamburger SV on 4 August, and was named the player of the matchday by leaving a deep impression on
kicker with two assists. After the end of the
2019–20 season, his goal against
Karlsruher SC was selected as Kiel's Goal of the Season. On 13 January 2021, he played full time and scored the fourth penalty in a
2020–21 DFB-Pokal match, where Kiel won 6–5 on penalties after drawing 2–2 against
Bayern Munich. Afterwards, Kiel reached the semi-finals of DFB-Pokal for the first time in history, but they were eliminated by
Borussia Dortmund. Kiel also finished third in the
2020–21 2. Bundesliga, qualifying for the promotion play-off. In the two-legged play-off, Lee scored a goal and provided an assist, contributing to all two of Kiel's goals, but they lost 5–2 on aggregate to
Köln.
Mainz 05 In July 2021, Lee joined
Bundesliga club
Mainz 05 on a three-year deal until 30 June 2024. Lee was named the player of the 22nd matchday by
kicker after dominating
Borussia Mönchengladbach including a goal and an assist on 24 February 2023. In that month, he was nominated for the Bundesliga Player of the Month by leading Mainz to three Bundesliga victories as well as having three goals and two assists, but lost to
Julian Brandt. He was also nominated for the Bundesliga Team of the Season because of his steady performance during the 2022–23 season, but failed to be selected. Lee seemed lethargic while Mainz earned only one win in the first half of the
2023–24 season, but he played a key role in saving his team from relegation during the second half of the season. Lee scored two goals in a 2–1 win over Bayern Munich on 14 December 2024, leading Bayern to their first defeat in the
2024–25 Bundesliga. During the 2024–25 season, he had seven goals and six assists (ten assists according to the standard of
kicker) in 33 league appearances, After coming on as a 60th minute substitute in a
league phase match of the 2025–26 Conference League on 6 November 2025, Lee had one assist and the winning goal, converting
Fiorentina's 1–0 lead into Mainz's 2–1 win. The goal was his first goal at UEFA competitions excluding qualifiers. ==International career==