Kim made his debut in 1998 as a vocalist in the boy band Shinhwa. Although he is not the lead vocalist, he began singing bigger parts on Shinhwa's 7th album, "Brand New". In one song from the album "Liar", Kim is the vocalist, and he is accompanied by Eric Mun's rapping. He also wrote, composed, and arranged a song on the album, titled "Set Free". Though he had branched out as a solo artist, he is part of Shinhwa and just released Shinhwa's 9th album.