In 2002, Jeong joined Munhwa Broadcasting Corporation's Voice Acting Division.

[3] After being a freelancer, Jeong made a brief appearance on a 2005 South Korean film Quiz King, playing his role as a television news reporter.

[citation needed] The voice actor became popular with his dub of Kiyomaro Takamine on Zatch Bell!, which has been one of his signature works.

In late 2011, Jeong once was on stage, portraying Lee Mong-ryong in a South Korean charity play Hyang-dan, Fly.

[4] He has recently been known for his voicing Shota Kazehaya on the Korean dub of a Japanese television animation series From Me to You, which made many fans of Jeong call him Jeong-jae-ha-ya (Korean: 정재하야; a compound word formed from Jeong Jae-heon and Kazehaya).