Lonnie McClanahan and Anthony Walker contributed 14 points apiece, Drew Charles had 12 and Greg Gainey 10 for the Mavericks (8-4, 2-0 Sun Belt), who shot 59.7 percent from the floor (40 of 67) to win their fifth straight game.
Texas-Arlington never trailed, opening with a 15-2 run and taking a 55-34 advantage into the break.
South Alabama (2-10, 0-2) also shot well, hitting 29 of 55 from the floor, including 18 of 28 from long range, and outscored Texas-Arlington 53-44 over the final 20 minutes. But the Jaguars were outrebounded 40-25 and took fewer shots in their seventh-straight loss.
Ken Williams had 18 points to lead five South Alabama players in double figures.
The win gave Texas-Arlington its first 2-0 conference start in three seasons.