Sophomore DeWanna Bonner led the Tigers with 27 points as she hit 10-17 field goals, including 5-8 three-pointers.
Making her first Auburn start, forward Trevesha Jackson produced a double-double with 14 points and 10 rebounds.
"She has a nose for the ball and a nose for the basket," Auburn coach Nell Fortner said of Jackson, a sophomore juco transfer. "She just finds a way to get the job done."
Trevesha Jackson (1) battles inside for the Tigers.
The Tigers got 17 points from sophomore guard Sherrell Hobbs and sophomore guard Whitney Boddie added seven points and 10 assists. Hobbs made 8-10 field goals.
Western Michigan built its big lead with hot shooting, hitting 71 percent from the field in the first half.
In the second half it was Auburn that got hot. The Tigers made 60.6 percent of their shots in the final 20 minutes to spark the comeback while holding WMU to 35.4 from the field.
For the game the Tigers hit 54 percent from the field to 53.2 for Western Michigan. The Tigers won the rebounding battle 42-33.
Both teams shot well from three-point range. Auburn hit 9-19 while Western Michigan, which fell to 1-6 this season, made 7-16. At the foul line Auburn made 14-25 and Western Michigan was 13-25.
Auburn tied the game at 75-75 on a basket by Jackson with 6:58 to play and took the lead for good at 78-77 at the 6:29 on a long-range three by Bonner.
"They showed us something today," Fortner said of her team. "I hope we don't get down like that again, but I liked the fight we saw."
The Tigers return to action to play Jacksonville State at 6 p.m. on Wednesday at Beard-Eaves Memorial Coliseum.