Oklahoma (3-0) went on a 13-0 run midway through the second half to stretch a 10-point halftime lead.
Davis hit two of his game-high six 3-pointers during the run and finished with 21 points. Davis went 6-for-10 from behind the arc and made more 3-pointers than Texas Southern, which went 5 of 20.
Pledger added a game-high 23 points, and Nick Thompson pulled down nine rebounds.
Kevin Galloway scored 19 points and recorded seven assists to lead the Tigers (0-3).
Oklahoma faces Kentucky on Monday to open the Maui Invitational. The Tigers continue their season-opening six-game road trip against Oregon State on Sunday.
Nike Men's Oklahoma Sooners Anthracite ELITE Stripe Performance Full-Zip HoodieShop
Maryland point guard Melo Trimble has withdrawn from the NBA draft and will return to College Park for his junior season, sources told ESPN.
Louisville's Chinanu Onuaku, who recently underwent a medical procedure to correct a heart rhythm issue detected during the combine, will keep his name in the NBA draft pool.
Andrew White III will return to the Nebraska men's basketball team next season after removing his name from the NBA draft.