The Wildcats (15-3, 3-2 Southeastern Conference) survived 13-of-29 shooting from the foul line to hold off the Tigers (11-6, 2-2).
Meagan Tucker hit a jumper with 1:07 left to bring Auburn within two points. The Wildcats worked 20 seconds off the clock and then called timeout. O'Neill missed two long jumpers in the final seconds, but Linnae Harper and Walker grabbed the offensive rebounds.
Walker missed two free throws with 6 seconds remaining. Tyrese Tanner, who scored 28 points, rebounded and threw it to Katie Frerking. O'Neill smothered her in the corner and Auburn couldn't get a final shot off.
Harper also had 13 points for the Wildcats.
Auburn starter Hasina Muhammad missed the game with an unspecified injury.