The Olympic gymnast won gold in floor exercise Tuesday, an hour after winning bronze on balance beam.
The gold is the first ever on floor exercise for a U.S. woman.
Raisman will leave London with three medals, the most of any of the American gymnasts.
Romania's Catalina Ponor won silver on floor, and Russia's Aliya Mustafina earned bronze.
World champion and pre-Olympic favourite Jordyn Wieber placed seventh. Wieber has not won any individual medals.
Raisman won her bronze on balance beam through a tiebreak, just days after a tiebreak cost her bronze in the individual all-around event.