Stevenson started her career by becoming Junior World Champion in 1998. In 2000, she won the 3rd place in taekwondo at the 2000 Summer Olympics's World Qualification Tournament and qualified for the 2000 Summer Olympics in Women's 67 kg. These achievements won her fame and drew the attention of martial arts superstar Jackie Chan who sponsored her while promoting his film "Shanghai Noon" in the United Kingdom. But in the 2000 Olympics she lost to Norway's Trude Gundersen in the semifinal and Japan's Yoriko Okamoto in the bronze match. The next year, she became a world champion in the 2001 World Taekwondo Championships's Women's Middleweight, defeating 2000 Summer Olympics gold medalist Chen Zhong in the final. She became the first British Taekwondo World champion.