Kim won a gold medal in the -73 kg class at the 2004 World Junior Judo Championships in
Budapest,
Hungary. At the
2005 Asian Judo Championships in
Tashkent, he won a gold medal in the -73 kg class. Kim was considered one of the Big Three Judokas of the -73 kg class in South Korea, along with
Lee Won-hee and
Wang Ki-chun. But in 2007, he moved up in weight to avoid the fierce competition, and won a gold medal in the -81 kg category at the
2008 Asian Judo Championships in
Jeju. At the
2008 Beijing Summer Olympics, Kim won the silver medal in the -81 kg class. In the preliminary rounds, he defeated 2006 European champion
Serguei Shundikov of
Belarus by points, and 2007 European champion
Robert Krawczyk of
Poland by
ippon. Kim edged out 2008 European champion
João Neto of
Portugal by points in the quarterfinals. In the semifinal, Kim beat 2005 World Champion
Guillaume Elmont of the
Netherlands. Despite defeating all of the European champions from 2006 to 2008 in the previous rounds, Kim lost in the final round to the 2005 European champion, Ole Bischof of Germany. Kim won his first major gold medal at the
2010 World Judo Championships held in
Tokyo, Japan. In the gold medal match, he defeated two-time Olympic medalist
Leandro Guilheiro of
Brazil by scoring a
waza-ari with
ouchi-gari in extra time. Kim went on to win gold by defeating
Srdjan Mrvaljevic of
Montenegro with a waza-ari by
osaekomi. In the
2012 London Summer Olympics, Kim won the gold medal in men's -81 kg division, defeating German rival, Ole Bischof. He announced his retirement on 1 May 2016. ==Achievements==