[2] In February 1996, Kim was first called up to the South Korean national team and made his senior debut at the Asian Winter Games in Harbin, China at the age of 16, where he won the gold medal in the men's 5000 metre relay together with Olympic champions Chae Ji-hoon and Song Jae-kun, and three medals in the individual events.

In March 1996, Kim also made his first appearance at the World Championships in The Hague, where he won bronze as a member of the 5000 metre relay team.

In January 1997, Kim competed in the World Junior Short Track Speed Skating Championships held in Marquette, Michigan.

In the tourney, Kim won all five events (overall, 500 m, 1000 m, 1500 m, 1500 m super final), easily dominating all other competitors including Rusty Smith, François-Louis Tremblay and Dan Weinstein every race.

Kim became the first short track speed skater to win the overall world championship titles both at junior and senior levels in the same year.

In February 1998, a year after winning the overall world championship title, Kim competed in the 1998 Winter Olympics in Nagano as a favorite.

Kim continued his successful run at the second 1999–2000 World Cup race in Salt Lake City, where he won the overall competition again with five gold medals and one silver finishing on podium in all disciplines.

Kim made a good recovery through the 2001–02 World Cup Series and was highly expected to win multiple medals at the 2002 Winter Olympics in Salt Lake City.

Controversy surrounded his disqualification at the 1500-metre race, where he crossed the line first in the final but was then disqualified for allegedly blocking Apolo Ohno.

[8] South Korean media accused Ohno of simulating foul, popularizing the term "Hollywood action" in Korea.

[10][11] The South Korean delegation threatened to boycott the Olympic closing ceremony to protest what they believed was biased refereeing.

[13] A month later, Kim won all possible six gold medals in the men's category at the 2002 World Short Track Speed Skating Championships (overall, 500 m, 1000 m, 1500 m, 3000 m, 5000 m relay), a feat achieved by no other man in the history of the competition.

Upon graduation from Korea University in early 2002, Kim signed a contract with the Dongducheon City Sports Club.

Kim competed in domestic competitions sporadically in 2003 and 2004, but finally announced his retirement in 2005 due to a chronic knee injury.

[15] U.S. Speedskating investigated Kim and the board concluded it did not have enough evidence to take legal action; the alleged victims never called the police.

[20] A series of exhausting confrontations and unfavorable local media reports left him frustrated and he finally came back to South Korea in November 2011.