James Harden scored 13 points and Jeff Pendergraph finished with 12 points and 11 rebounds for the Sun Devils (20-5, 9-4 Pac-10), who won their four straight game -- and clinched their first back-to-back 20-victory seasons since 1980-81.
DeMar DeRozan had 16 points and 10 rebounds for USC (15-9, 6-6), which lost its third straight. Taj Gibson, Daniel Hackett and Dwight Lewis had 11 points apiece.
Floyd was tossed with 47.9 seconds left in the second half after he charged onto the floor to argue a charging call against Hackett, complaining that one official had called a blocking foul against Arizona State.
After playing tight throughout the first half, the Sun Devils finished the period with a 10-2 run that allowed them to take a 29-20 lead into the intermission.
USC briefly took a 38-37 lead at 7:34 of the second half but Arizona State put together a 15-2 run to take the lead for good.
The Trojans pulled to within 57-51 with just over 2 minutes left but could not find a way to close the gap after that.