In 2003, Kim spend most of his sophomore season in the reserve league, but was added to the Unicorns' first team after the September roster expansion and batted a respectable .368 (7-for-19).

Kim came back to the KBO League in 2008 when he finished the military service, but was on the Heroes' roster off and on for the 2008 season, batting a career-low .056 (1-for-18), playing in only 16 games as a substitute infielder or pinch hitter.

Kim hit the first home run of the 2010 KBO baseball season off Lotte Giants starter Ryan Sadowski, going 2-for-4 in the Heroes' opening game on March 27.

In July, Kim moved his position to third base and became a permanent fixture as Heroes' franchise third baseman Hwang Jae-Gyun was traded to the Lotte Giants.

He was ranked ninth in the KBO league in triples (3), tenth in stolen bases (28), eleventh in walks (70) and twelfth in at-bats (447), posting career-highs in most of the offensive categories.