He is a member of South Korean boy group Super Junior and has further participated in its subgroup, Super Junior-T as well as project group with TRAX's Jungmo, M&D.Aside from group activities, he participated in various television dramas, appeared as a radio DJ and television presenter.He's appeared “Lady Hee Hee” throughout Super Show 3, as well as SM Town in Paris.
In September 2013, he became a regular cast member on the JTBC's variety program Ssulzun (War of Words) it was his first project after releasing from his mandatory military enlistment but on July 2014 he posted a photo in his personal Instagram account and poured his heart and thoughts regarding his last appearance in the program.
In Heechul’s last recording for the show, he mentioned about having the pressure of talking about the people close to him.
Heechul wrote the lyrics and directed the music video for the song, while Jungmo produced and performed the instrumental.
Their first live performance was at Mnet’s summer awards ceremony 20’s Choice on July 7.
In 2011, he formed a project group with label mate Jungmo of TRAX called M&D (meaning "Midnight and Dawn" or "Miari and Dangae-dong", after the members' hometowns).