His parents were future North Korean dictator Kim Jong Il and his consort, Ko Young Hee. He had an older brother named Kim Jong Chul and would later have a younger sister named Kim Yo Jong.

While Kim Jong Un's official birth year is 1982, various reports suggest that the year was changed for symbolic reasons, including that it was 70 years after the birth of Kim Il Sung and 40 years after the birth of Kim Jong Il.

However, a recent move by the US Treasury Department to sanction Kim Jong Un listed his official date of birth as January 8, 1984.