At the 2002 Winter Olympics, Choi won a silver medal in the 1500 m and was a member of gold medal-winning relay team in 3000 m relay. She was the World record holder for 1500 m at the time.
Choi's career heights came between 2002 and 2006 Winter Olympics. She was the Overall World Champion in 2003 and in 2004. She also won the Overall World Cup title for 2003–2004 season.
At the 2006 Winter Olympics she equalled her achievements from the previous Olympics, winning a silver medal in the 1500 m and won gold in the 3000 m relay. She was disqualified in the finals of the 1000 m.