Kim Jong-hyeong was born on April 13, 2002, in Gumi, North Gyeongsang, South Korea.

[1][2] Before debuting, he was leading a dance club at school and was even elected as the overall vice president during his elementary days.

[8] In May 2022, he and fellow member, Jaechan, became fixed radio DJs at KBS Cool FM's Station Z.

[9] On May 18, 2023, Dongyo Entertainment announced the formation of Nine to Six, a duo sub-unit consisting of Jonghyeong and Mingyu.

[14] He also portrayed Polidori, an English writer and physician, in the 2023 South Korean musical Mary Shelley in December.