Kim was a first round pick of the Hanhwa Eagles in 2001 following a successful youth career. He made his KBO debut on April 17, 2001 as a starting first baseman against the Hyundai Unicorns. As a rookie in 2001, he hit 20 home runs and drove in 54 runs with a .335 batting average. After the 2001 season, Kim was honored with the Rookie of the Year Award. He became the first Eagles player to win the award.
In 2002, Kim experienced a sophomore slump, batting .255 with 7 home runs, but came back strong in 2003 to bat .319 with 31 home runs and 95 RBIs.
From 2003 through 2005, he notched three consecutive seasons batting .300+.
His stats dipped slightly in 2006 and 2007, but he broke out again in 2008, batting .324 with 31 home runs and 92 RBIs. He was first in home runs and slugging percentage, 4th in RBI, and 5th in batting average.