A World Junior Champion in 2002, she went on to win the 100 m at the 2003 Pan American Games and claimed the NCAA title over the distance for the University of Miami the following year.

She has also featured as part of the American 4×100 meter relay team, winning gold medals at the 2005 and 2007 World Championships and at the 2012 Summer Olympics.

Williams is one of six athletes to have won a medal in both the Summer and Winter Olympic games, as well as the first American woman to do so.

Williams is a silver medalist in the 100 meters at the 2004 Summer Olympics and a 4-time medalist at the World Championships in Athletics, where she won (together with Angela Daigle, Muna Lee and Me'Lisa Barber) a gold medal in the 4x100 m relay in 2005 and 2007, as well as gold and silver in the 100m in 2005 and 2007 editions of the meet.

Marion Jones, who ran the second leg, and Williams failed to complete the baton exchange within the 20-meter passing zone, resulting in disqualification of the U.S. team.

Williams, Allyson Felix, Muna Lee and Carmelita Jeter finished with a time of 41.58 seconds, bringing them to eighth on the all-time list.

[7] In the 2012 Olympics in London, Lauryn Williams ran the anchor leg of 4 x 100 meter relay for USA in the qualification round.

[8] On February 19, 2014 Williams along with Elana Meyers won the silver medal at the 2014 Winter Olympic Games.