Arizona State (11-8, 3-4 Pac-12) trailed by 16 at halftime but outscored the Trojans 40-17 in the second half.
Cassie Harberts, who led USC (7-11, 4-3) with 24 points and 14 rebounds, made a free throw with 2:30 to play to extend the Trojans' lead to 53-49. But they did not score again, and Amukamara made her 3-pointer with 1:44 to play, and Haley Videckis' two free throws with 1:20 remaining put ASU in front to stay at 54-53.
Amukamara and Janae Fulcher led the Sun Devils with nine points each. Seven Sun Devils finished with six points or more.
Harberts had 19 points and 10 rebounds in the first half to help USC to a 36-20 lead.