Lillard added eight rebounds and four assists for the Wildcats (3-0). Kyle Bullinger had 11 points and 16 rebounds.
Daman Starring scored a career-high 21 points for UCI (0-3). Michael Wilder and Derick Flowers added nine points apiece.
Chris McNealy hit two free throws with 5:44 left for a 59-57 Irvine lead before the Wildcats went on a 16-3 run, capped by a 3-pointer from Lillard, to go up 73-62 with 1:38 remaining.
Weber State hit 7 of 8 free throws in the final 54 seconds to seal the victory. For the game, Weber State hit 26 of 31 free throws, including 20 of 23 in the second half. UCI was 22 of 34 from the foul line.