Kai was born in Seoul, South Korea. He was cast into S.M. Entertainment after winning in the company's Youth Best Contest in 2007. Prior to joining S.M. Entertainment, Kai was trained in ballet and jazz dance. In 2008, he made a brief appearance in TVXQ's music video, "HaHaHa Song" along with EXO-K's Suho and Chanyeol. Kai was the first of the twelve members to be formally introduced through teaser trailers; his teaser was released on December 24, 2011. Kai appeared in twelve more trailers in the next three months, and performed with EXO-M's Lu Han, Tao, and Chen on SBS's Gayo Daejun event on December 29, 2011.