After Hargrove opened the second half with a steal and dunk to put Auburn up 45-32, Vanderbilt kicked it into gear with an 11-2 run to draw to within 47-43 as the momentum changed in front of a sold out crowd of 14,316.
John Jenkins's 24-foot 3-pointer allowed the Commodores to regain the lead for good at 55-53 with 11:36 remaining, capping an 18 point turnaround.
With Vanderbilt holding a 65-60 lead, Auburn's Sullivan was whistled for a charge that erased his made layup. With a made free throw to follow, the lead could have been cut to two with 5:47 remaining. The Commodores then quickly scored six straight points to push their lead to 71-60 with 4:32 to play, and the lead never dipped below eight points the rest of the way.
"Vanderbilt played well in the second half," said Auburn head coach Jeff Lebo. "They scored at a high clip in the second half and got some easy buckets and kind of wore us down a little bit more than anything.
"I loved the way we played to start the game in the first half. I thought we moved the ball well. We shot the ball well. We got high percentage looks. We defended pretty well. They are good. What makes them so hard to defend is they have nice balance. They can score inside, and they can score outside."
Auburn (10-10,1-4) jumped out to a quick 20-10 lead almost seven minutes in, but Vanderbilt scored seven straight points. The Tigers used a 9-0 run to push their lead back up to 33-19 on a Reed 3-pointer from the left corner with 5:38 on the clock.
A Ty Armstrong tip-in and a Hargrove layup gave Auburn its largest lead at 41-25 with just over three minutes to go before holding a 43-32 lead at the half.
"We got off to a really good start," said Hargrove. "We knew they were a great team and were going to make a run in the second half, and we tried to poise ourselves and the younger players. They made a run. They have a great crowd, and we just couldn't regain composure."
Vanderbilt started SEC play 4-0 for the first time since 1965-66 as it ran its overall record to 15-3.
Auburn shot 46.3 percent from the field for the game and 35 percent (7-of-20) from 3-point range. The Tigers made 17-of-24 free throw attempts while the Commodores finished the game shooting 53.7 percent from the field, 33.3 percent (5-of-15) from 3-point range and 19-of-25 from the foul line.
Auburn plays host to Ole Miss on Thursday at 8 pm Central on ESPNU and Alabama next Saturday at 3 pm Central on the SEC Network.