O'Neal's AAU team, California Supreme made the announcement of his verbal commitment via Twitter.
The five-star junior recruit from Crossroads School in Santa Monica, Calif., is ranked No. 19 in the ESPN 60 for the class of 2018.
The 6-foot-9, 210-pound O'Neal averaged 14.1 points and 7.3 rebounds a game last season for Crossroads School.
UCLA, Kentucky and LSU -- his father's alma mater -- were among the schools in contention for O'Neal.
Arizona head coach Sean Miller now has two five-star prospects committed for the 2018 class, with O'Neal joining small forward Emmanuel Akot at the Pac-12 program.