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).

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.

[8] Key participated in labelmate Xiah's solo performance of "Xiahtic" in TVXQ's concert 2009: The 3rd Asia Tour Mirotic in Seoul.

[12] In 2012, Key collaborated with Leeteuk of Super Junior on a song called "Bravo" for the drama History of a Salaryman.

The musical ran from March 28 to June 10 at the Blue Square, Samsung Card Hall, in Hannam-dong, Seoul.

The production started on December 14, 2012, and continued until February 9, 2013, at the Opera House in the Seongnam Arts Center.

[20] According to the members, it was their idea to form a duo since they were close friends, but they weren't thinking of a musical collaboration, instead of photoshoots and similar activities.

Key provided vocals for the track "Hold On", which they performed together at the Ansan Valley Rock Festival on July 25, 2015.

[29] He took further musical roles in Chess[30] and In the Heights,[31] the latter of which was later performed with Japanese subtitles at Kanagawa Arts Theatre in Yokohama in 2016.

[32] Key starred in his first play as Byeong-gu in Save the Green Planet!, based on the 2003 film of the same name.

[38] In the drama, Key plays the role of Gong Kyung-soo, a skater and a hacker whose mother went missing due to a crime[39] and received positive reviews for his acting skills.

The original Korean verses reflect the song's overall meaning, as Key asks a lover to stop pushing-and-pulling[43] and were written by the singer himself.

[46] Two weeks later, the single "Forever Yours", featuring Key's close friend and former Sistar member Soyou, was pre-released on November 6 along with a music video.

[47] On November 26, his first studio album, titled Face, was released, alongside a music video for the lead single "One of Those Nights", featuring Crush.

[50] His first solo concert in South Korea, titled The Agit: Key Land, was held in February 2019 in Seoul and consisted of 11 sold-out performances.

[57] On August 30, 2021, Key released the single "Hate That...", featuring Taeyeon, serving as the pre-release for his upcoming album in September.

[81] In the media, his fashion has been compared to that of fellow idol G-Dragon; both are known to eschew trends in favor of pursuing their own distinct style.

For instance, he collaborated with designer Ko Tae-yong on self-designed sweatshirts depicting his dogs and sold them for charity.

The costumes for Shinee's 2015 single "View" were based on Key's ideas, adopting a vintage, skater-inspired aesthetic at a time when other groups mostly wore uniforms.

In March 2017, Key worked with model Irene Kim to design new products for fashion brand Charm's.

[94] In 2021, he was selected as a model for health and beauty store Olive Young alongside labelmate Taeyeon, in a campaign targeting younger consumers.

[95] He launched a skincare line named Key: Face in collaboration with Youlief, for which he personally designed the products.

It sold over 3.5 million bottles in four months, making it the fastest-selling product in the Jinro Tonic line, and contributing to an 83% increase in annual sales.

[102] In 2012, Key and his fans from Korea, China, Japan, Taiwan, Singapore, Thailand and seven other countries donated 2.12 tons of rice to World Vision, which was used to feed 17,000 undernourished children and elderly people across 11 cities.

[105] In the same year, Key collaborated with designer Ko Tae-yong and sold sweatshirts depicting his dogs.

[106] Key visited Kyungpook National University Hospital in 2019 ahead of his military enlistment and made a donation of 10 million won to support treatment costs.

[107] In January 2022, he donated products from his Youlief skincare line worth 12 million won to the Korean Unwed Mothers' Families Association.

[108] In 2023, an online commenter drew attention in the media after thanking Key for covering the cost of their son's blood-cancer medication.