Travis Souza hit five 3-pointers for 15 points and Luke Nelson added 13 with eight assists for the Anteaters (15-10, 8-3 Big West).
The game was tied at 29 at the half before Irvine hit 7 of 10 3-pointers to pull away.
Stefan Jankovic had 18 points and 15 rebounds for Hawaii (18-10, 6-6) and Negus Webster-Chan had 16 points.
Hawaii was just 9 of 33 from the field in the second half, finishing 6 of 19 behind the arc while Irvine went 10 of 18.
Irvine never trailed in the second half but didn't pull away until a 10-2 run made it 61-48 with 6:34 to play.