Key

Aside from group activities, as a singer, he has collaborated with various artists, and formed the duo Toheart with Woohyun of Infinite. He made his debut as a soloist in November 2018 with the release of the digital single "Forever Yours", and his first studio album, Face, was released later that month. His second album, Gasoline, was released in 2022. Key has also contributed to songwriting for himself and Shinee.

As an actor, he was cast in multiple musicals, such as Bonnie & Clyde (2013), Zorro (2014), and Chess (2015). He has since widened his field as an actor by taking part in several television drama roles, like Drinking Solo (2016) and The Guardians (2017).

In 2015, Key became active as a fashion designer and took part in numerous projects. For instance, he collaborated with Bridge Shop House to design Shinee concert outfits, and worked with model Irene Kim and the brand Charm's to design fashion apparel. Due to the success of his works, Key was later appointed as a fashion director for the group. Since 2020, he has gained prominence as a television personality, appearing on the variety shows DoReMi Market and I Live Alone as a cast member. He has received the Excellence Award from the MBC Entertainment Awards in recognition of his variety performances.