Felix took to the track again on August 10, 2012, as part of the women's 4 × 100 meters relay team with Tianna Madison, Bianca Knight, and Carmelita Jeter. The foursome won with a time of 40.82 seconds, breaking the long-held world record of 41.37 seconds, set by East Germany in October 1985. On the final night of athletics, August 11, 2012, Felix ran a 48.2-second leg on the U.S. women's 4 × 400 meters relay team with DeeDee Trotter, Francena McCorory, and Sanya Richards-Ross, winning in a time of 3:16.87, the third-fastest time in Olympic history behind the Soviet Union and the United States at the 1988 Summer Olympics, and the fifth-fastest time overall, up until that point.