Southern Miss (0-3) had never lost to William Carey (2-3) in nine all-time meetings. The average score in those previous contests was 86-55.
Donta Pittman scored 14 points while Donnell Nicholes and Emmanuel Davis scored 13 and 12 points, respectively, for the Crusaders.
William Carey built an early 13-5 lead and pushed it to 50-33 by halftime.
A Pittman 3-pointer made it 63-39 with 16:28 to play in the game. The Golden Eagles used a 33-16 spurt to close to 79-72 on Cortez Edwards' layup. But Garrett's 3 pushed the lead back to 10, and Southern Miss only shot 3 for 9 from the floor the rest of the way.
Khari Price led Southern Miss with 20 points.