Picked up skating at the age of 7 at her mother's encouragement. Her talent quickly became evident as she began to dominate her older competition.

In 2003, at age 12, she became the youngest lady to win the Korean senior national title. Came to international prominence in the 2004-2005 season when she placed second at the Junior Grand Prix Final and again at the World Junior Figure Skating Championships, earning Korea's first medal at an ISU Championship. Following on her success of the 2004-2005 season, proceeded to win every junior level competition in the 2005-2006 season, her final junior eligible year.

Made her senior international debut at 2006 Skate Canada where she won a bronze medal and went on to win a gold medal at the 2006 Trophée Eric Bompard. It was the first ever win for a Korean figure skater at a senior international competition.

Later in the season, won the 2006 Grand Prix Final in St. Petersburg, Russia.

In January 2007, was diagnosed with early-stage lumbar disc herniation and did not compete at the South Korean Championships. Despite not competing at Nationals, she was selected to represent Korea at the 2007 World Figure Skating Championships.

In March 2007, participated in the 2007 World Championships in Tokyo and led the competition after the short program by setting the short program record for the highest score under the ISU Judging System. She placed third overall.

Started off the 2007-2008 season winning both the Cup of China and the Cup of Russia. At the Cup of Russia, she set the record for the highest score ever under the ISU Judging System for her long program. Continued her successful season in Turin, Italy, where she defended her Grand Prix Final title.

She chose not to compete at the 2007-2008 South Korean nationals. Withdrew from the 2008 Four Continents Figure Skating Championships a week before the event due to a hip injury. She is currently focusing on thorough recovery, rather than training, before the 2008 World Championships take place. Won the bronze medal at the 2008 World Championships for the second successive year in a row. Although she won the free skating portion of the event, a fall on the triple lutz jump in the short program left her in third place overall. Has been assigned to the 2008 Skate America, 2008 Cup of China for the 2008-2009 Grand Prix Season.