[2] Just after graduating Gangseo Senior High school, he entered directly into the Korean entertainment industry, as an official manager of comedian Lee Hwi-jae.

This segment was a parody of segment "Brain Survivor" from Sunday Sunday Night, and his role was a foolish quiz-challenger, including the creation of fad words such as "This is like, killing me twice" (이건 나를 두 번 죽이는 거예요)[3] In his later career, he has become a top Korean comedian.

With the huge success of "No-brain Survival", he eventually become an official member of top-rating comic variety program Infinite Challenge since March 2006 and as the second eldest member, he is positioned as "the third-in-command" (3인자), putting him below the host-in-chief Yoo Jae-suk and fellow co-host Park Myung-soo.

Soon, he re-created his character as "Super-Fatty" (뚱뚱보), in contrast with the former "Fatty" (뚱보) and his long-time colleague on this programme, Jeong Hyeong-don.

On Infinite Challenge, he is noticeable for three things: his tall and big stature, his extraordinary appetite, and his degree of slowness in judgment.

By then Haha had temporarily left the program to fulfill his military service, and Jun Jin's addition to the team resulted in a change of arrangement in 2008.

He is highly acclaimed, not only by fellow cast members, but also by other Korean celebrities, for his extraordinary appetite, which gained him the nickname the "God of Eating" (식신/食神 Shikshin).

He has an aptitude for working with numbers and calculating sums quickly and correctly, gaining him another nickname in direct contrast with his foolish charisma, "Secretary Jung" (정총무).

[10][11] In 2021's episode of Learn Way (season 2), he was the teacher that taught Mijoo to make Makgeolli, as he is also a certified traditional Korean alcoholic drinks sommelier.