[2] In 2015, Mark and other SM Rookies members starred as Mouseketeers in a Korean revival of The Mickey Mouse Club, which aired on Disney Channel Korea.

The following month, Mark featured on Henry Lau's "Going Through Your Heart", an original soundtrack for the KBS drama, Sweet Stranger and Me.

In January 2017, Mark joined High School Rapper, a survival hip hop reality TV show that aired on Mnet.

He teamed up with Parc Jae-jung to release "Lemonade Love" on July 21, also through SM Station, which was produced by former labelmate Henry Lau and Yoon Jong-shin.

[13] In October 2018, Mark released the song "Dream Me" with Red Velvet's Joy for the soundtrack of the KBS drama The Ghost Detective.

On April 14, SM Entertainment announced through an official statement that Mark would be rejoining NCT Dream, thus abolishing their original age-based graduation system.

[23] On March 30, 2023, it was announced that Mark would release his new solo song and second single, "Golden Hour", on April 7, as part of NCT Lab.

The single "Fraktsiya" is a hip-hop track defined by its powerful 808 bass and highly repetitive synthesizer sounds over a house-style chord progression.

'Fraktsiya,' which means 'spy' in Russian, is referenced in the lyrics to describe Mark and Lee Young-ji's experiences navigating between K-pop and hip-hop.

[1] Subsequently, the release of his solo album, originally scheduled for February 2025, was postponed to April 2025, with SM Entertainment stating that the delay was to 'ensure better quality'.