She competed at the second Olympic triathlon at the 2004 Summer Olympics. She was the first U.S. triathlete to win an Olympic medal by taking the bronze in 2004 in Athens. She placed third with a total time of 2:05:08.92. Her split times were 19:02 for the swim, 1:08:58 for the cycling, and 0:37:08 for the run. Through the 2012 Olympic Games, she is still the only U.S. triathlete to bring home an Olympic medal in the sport.
Williams obtained a Master of Science in Aerospace Engineering Sciences and was working toward becoming an astronaut when her success at triathlon convinced her to give it a try.