Kim began garnering attention in 1978 when he won the flyweight (-51 kg) gold medal at the Asian Junior Amateur Boxing Championships in Karachi, Pakistan.

In 1979, Kim won the gold medal in the flyweight division at the CISM Amateur Boxing Championships in Caracas, Venezuela, beating Oudahi Mohammad Amin of Algeria via first-round knockout in the final bout.

Four months later he fought Little Bangoyan for the vacant Oriental and Pacific Boxing Federation (OPBF) title, capturing it with a twelve-round decision.

For the next year Kim made five defenses of his OPBF title against the likes of Lito Cortez (KO 2), Rolando Navarro (PTS 12), and Fel Malatag (TKO 6).

On 3 January 1985, he fought countryman and reigning International Boxing Federation super bantamweight champion Suh Sung-in.