Nic Campbell added 13 for the Anteaters (10-11, 4-3 Big West).
Long Beach had a 13-5 run in the opening minutes of the second half, then narrowed the lead to 71-70 at 6:11. But UC Irvine stretched the lead to 80-72 at 2:05 after a 3-pointer by Michael Hunter.
Long Beach pulled within one point, 82-81, after Johnson's three-pointer with 30.8 seconds remaining. Chuma Awaji then hit six-of-six free throws in the final 15.3 seconds.