[2][3] Hoon originally debuted as a solo ballad singer under his real name and released an extended play Pure & Love with the title track "Bus" on September 9, 2009.

[6] After the departure of Alexander and Kibum, NH Media announced that Hoon and Paran's AJ would be joining U-KISS.

[7] He made his debut as a member of U-KISS through the group's fifth mini album Bran New Kiss which was released on March 30, 2011, with the title song "0330".

Later that year, it was announced that Hoon and Dongho would star in Super Action TV's Holy Land, a four-part movie about rebellious high school students.

[16] On January 24, 2022, Hoon signed an exclusive contract with Tango Music where he also returned with his groupmates Soohyun and Kiseop.