At just 18 years old, Felix competed in her first Olympics, the 2004 Summer Games in Athens. Competing in the 200-meter race, she finished second, and earned the silver medal. In 2005, she became the youngest champion to compete at the World Championships, and two years later, she became only the second female to win three gold medals at a single World Championships.

At the 2008 Olympic Games in Beijing, Felix ran a personal best of 21.93 in the 200 meters taking a second silver medal. She also earned one gold medal that year, with the women’s 4-by-400-meter relay team.

At the 2012 Olympic Games in London, Felix struck an independent gold medal in the 200, respectively, with a time of 21.88 seconds. Felix went on to compete in the 4-by-100-meter relay, and, along with teammates, won a gold medal. The relay team also set a new world record, with a time of 40.82 seconds (the previous record was 41.37 seconds, set in 1985 by East Germany.