In 2007 she won the American (USATF) championship in the 400m in a personal best time of 49.64.
At the 2004 Summer Olympics, Trotter placed 5th overall in the 400 metres with a personal best time of 50.00s. Trotter was part of the US team which finished first in the 4×400 meters relay. In 2010 Athens 4x400m relay team member Crystal Cox, pleaded guilty to a doping violation which has put the entire gold medal team at risk of losing their medals. Legal proceedings are still in process and no decision has been determined regarding the disqualification of the entire relay.
An NCAA champion, she was the first Tennessee Lady Vol to pursue a professional track and field career before completing her collegiate eligibility.
Trotter ran in the women's 400 meters race in the 2008 Summer Olympics, but failed to qualify for the finals due to a major knee injury. In the 2012 Olympics in London she won the bronze medal in the 400 meters in a time of 49.72.