After he was discharged from military service, he worked on his music career on his own until he joined Boohwal, which is considered by many to be the living legendary rock group in South Korea.

[5][6] In an interview, Jung explained that a performance of "Don't Stop Me Now", by Queen, gave such an awe-inspiring impression that it motivated him to become a musician.

[7] After completing military service in 2004, Jung signed with a recording studio of a composer he had befriended and prepared his career further.

[8] In a radio show Boohwal's leader Kim Tae-won talked about how, in the audition, he heard Jung Dong-ha singing "고해/Gohae/Confession", which is one of well known classic Korean pop song, and was so amazed that he picked him as the new vocal for the band on the spot.

In May, Jung was featured on a song titled "Aaeburrlae" and in July, he participated in an O.S.T of Korean broadcasting station MBC's Drama Chinku, Urideuluijeonseul.

[19] In February, he was cast as the show host of a music program called "Live H", and started his appearance in the broadcasts.

In March, 25th Anniversary: Retrospect II was released and Jung participated in the supporting album of the 2010 FIFA World Cup called The Shouts of Reds.

Current members of Boohwal include Kim Tae-won, Seo Jae-hyuk, Chae Jae-min and Jung Dong-ha.

Jung is currently the youngest member in Boohwal, presenting as much as fifteen years of age difference.

[25] The latest official album of the band 25th Anniversary: Retrospect has two parts, released in August 2009 and March 2010, respectively.

When inquired about why Jung Dong-Ha decided to leave Boohwal even after becoming the longest running vocalist of Boohwal by You Hee-yeol in the KBS musical program You Hee-yeol's Sketchbook, Dong-Ha answered that he wanted to discover a new side of himself and his singing (which he realized after becoming a contestant of KBS's other musical program "Immortal Songs: Singing the Legend").

The project's intent was to help students of music make breakthroughs to penetrate the realm of career in musicianship.