At the 2006 Winter Olympics, Lee made a thrilling move to pass Apolo Ohno on the final lap of the 1000 m, securing a 1-2 finish for Korea in the event.

Lee also won gold in the 5000 meter relay along with countrymen Ahn Hyun-Soo, Seo Ho-Jin and Song Suk-Woo.

The Korean team defeated two-time defending Olympic champion Canada with a powerful pass by Ahn in the closing laps.

At the 2009 World Short Track Speed Skating Championships in Vienna, Lee became the Overall World Champion[5] and went on to win his domestic Olympic Trials a few months later, becoming the leader of the Korean Short Track Team, as well as one of the top contenders to win gold in 2010 Winter Olympics in Vancouver, British Columbia, Canada.

At the 2010 Winter Olympics, South Korea was in position to sweep the 1500m until Lee accidentally crashed into Sung Si-Bak and took them both out of contention entering the final turn, giving the silver and bronze medals to Americans Apolo Ohno and J. R. Celski, respectively.