Felix began as a trainee at JYP Entertainment in December 2016, and after undergoing two months of training without being assigned to a group, he was personally chosen by Stray Kids' leader, Bang Chan, in February 2017, making him the sixth member of the band to be selected.
Felix continued to train with Stray Kids until the broadcast of the survival show, also titled Stray Kids. During this show, he faced elimination in the eighth episode, decided by Park Jin-young, the founder of JYP Entertainment. However, following careful consideration and a fan vote, Felix was reinstated in the group in the following episode.
Stray Kids then released their pre-debut EP Mixtape, before making their official debut with the EP I Am Not on 25 March 2018.
Individually, he was the host of the music program Pops in Seoul from July 2019 to January 2020.
In June 2022, Felix featured on his labelmate Nayeon's "No Problem" from her debut EP Im Nayeon.
His first solo song "Deep End" was included on Stray Kids' compilation album SKZ-Replay in December 2022, and during the group's 5-Star Dome Tour in 2023, he first performed his unreleased song "Rev It Up".
Felix made a cameo appearance in the music video for his labelmate NiziU's South Korean debut single "Heartris" in October 2023.
In February 2022, Felix was diagnosed with intervertebral disk herniation, which limited his performance in the group's SKZ Chocolate Factory fan meeting.
In November 2023, Felix was named one of GQ Korea's Men of the Year, and featured on the cover of GQ Korea's December issue.