Walker's score represented the 12th, and final, lead change in a game that saw each team seemingly steal momentum before exchanging buckets down the stretch.
"This was our biggest win of the year," said a tired-looking Jim Calhoun after the game.
The two teams exchanged baskets early, with the Longhorns taking the game's biggest advantage at 20-16 before Connecticut scored four straight to tie the game at 20.
But the Longhorns broke the game open a bit by going on a 9-0 run culminated in a Cory Joseph fast-break lay-in. After exchanging two points, Texas again led by nine at 31-22, but UConn made its run. Donnell Beverly made a pair of free throws and Kemba Walker added his first bucket on a jumper. After Gary Johnson hit a fadeaway, Walker drained a three pointer.
The Huskies were able to cut the lead to three just before halftime when Charles Okwandu converted a three-point play. But then the Huskies fouled Joseph while he was dribbling down the clock. Joseph converted both free throws for a 37-32 halftime advantage.
In the second half, the Longhorns stretched the lead out to as many as seven, for the last time at 48-41 when Joseph earned a goaltending call at the 15-minute mark. But Connecticut clawed back when Napier banked in a three-pointer for a 58-56 advantage with 10:07 left. The lead change marked the Huskies' first advantage since the 10:53 mark in the first half.
UConn continued to surge, even taking a nine-point lead with 6:02 remaining on another Napier three-pointer, making the score 68-59. Then it was Texas's time to take part in a comeback. The Longhorns went on a 12-2 run, taking the lead back with 1:32 left on a J'Covan Brown double-clutch jumper. Walker responded with a three-point play on a tough lay-up and free throw, while Brown sank a pair of free throws.
The Longhorns had the best chances to win in regulation, the first coming when Gary Johnson had his shot blocked by Alex Oriakhi with 10 seconds left on a play where the Longhorns wanted a goaltend. But they got the ball right back when freshman Roscoe Smith scooped up the rebound and — thinking there was no time left — attempted a last second shot. But the shot cleared the basket and went out of bounds, giving Texas a second attempt with more than seven seconds left. Brown's pull-up jumper attempt fell short.
The two teams were back-and-forth in overtime, with UConn garnering the biggest lead when Walker hit a miraculous three-pointer with 2:14 left. The Longhorns knocked the ball loose late in the shot clock, and Walker was forced into a one-handed heave from 40 feet from his hip. The shot swished through, giving the Huskies an 80-77 lead.
"It looked like he threw it up underhanded," said Jordan Hamilton. "I guess God was on their side."
The Longhorns earned the lead one last time following a floater from Joseph and a jumper from Hamilton.
That set up Walker's final attempt. Earlier in overtime, Walker drew a foul on Dogus Balbay by faking him into the air. Walker again found himself one-on-one with Balbay, and used a similar step-back move. While playing tight defense, Balbay admitted that he was a bit late to jump for fear of giving up the foul, and that was all the opening Walker needed.
Still, Texas had one more chance with 2.4 seconds left. Hamilton was doubled, forcing Brown to throw across court to Joseph. Joseph's initial attempt was stripped by Napier, and his second attempt was off-balance and failed to draw iron.
Walker finished with 22 points, though Texas forced him into an 8-27 shooting night. Napier scored 15 points. Walker and Napier combined to score 30 of their 37 points in the second half and overtime. The Huskies were also dominant on the boards, thanks to Alex Oriahki, who grabbed 21 rebounds, including 10 offensive. Smith and Oriahki combined for 24 points of their own.
Overall, the Huskies grabbed 52 rebounds to Texas's 42, with UConn grabbing 23 boards on the offensive end.
"We did a good enough job (defending Walker)," said Texas coach Rick Barnes. "We didn't do a good enough job on the boards."
Texas had five players in double figures, led by Hamilton and Brown with 20 apiece. The Longhorns were again plagued by free throw woes, making just 14-of-23. UConn was 12-14 from the stripe.
"I think the biggest thing that you want from your kids is for them to never be outworked and never be outwilled," said Calhoun, the longtime UConn coach. "In the end, Kemba Walker was Kemba Walker."
"I'd vote for him," said Barnes, when talking about Walker's potential National Player of the Year status.
UConn moved to 12-2 with the victory, while the Longhorns fell to 12-3 with the loss. Still, Barnes said he was proud of the way the team fought back from adversity.
"We can play with anybody," Barnes said. "There's no question about it.
"I just think that we could really be good," Barnes added. "But we're not there yet."