He was one of the younger brothers of Kim Il Sung, the first supreme leader and founder of North Korea.

Kim was born on 12 June 1916 in the Mangyongdae neighborhood of Pyongyang, when the peninsula was still under Japanese rule.

His parents were Kim Hyong-jik, a Korean independence activist, and mother, Kang Pan-sok.

His two brothers were Kim Il Sung, the first supreme leader of North Korea, and Kim Yong-ju, who became Honorary Vice President of the country's Supreme People's Assembly.

His maternal grandfather was a Protestant minister, and his father attended a missionary school.