Wall's sensational slam finished off a clean sweep for the Washington star, Paul George and Terrence Ross in the contest's new battle format, helping the Eastern Conference earn a 2-2 tie against the West on All-Star Saturday night.
Answering Sacramento rookie Ben McLemore's dunk in which he leaped over Shaquille O'Neal seated in a king's throne, Wall took the ball from Wizards mascot G-Man, who held it above his head, then brought it down between his legs and slammed down a two-handed reverse dunk.
"It was only my second time doing it. My first time was on Thursday," Wall said.
Judges Dominique Wilkins, Magic Johnson and Julius Erving all gave the victory to Wall in his matchup, after picking George over Harrison Barnes, and defending champion Ross over Damian Lillard in the first dunk contest with three All-Stars since 1988.
San Antonio's Marco Belinelli won the 3-point contest, and Lillard and Utah rookie Trey Burke won the skills challenge for the West's two victories. Miami's Chris Bosh, Wilkins and WNBA star Swin Cash won the night's first event for the East, the shooting stars.
The league tried to jazz up All-Star Saturday for its return to New Orleans, with a number of tweaks to the format that weren't all positively received.
The skills challenge became a team relay format, but the biggest change was in the dunk contest, which was broken into two parts. The first was the freestyle portion, where the teams had 90 seconds to execute as many dunks as they could, before the three 1-on-1 matchups in the battle format.
The East had already clinched that part by winning the first two, but Wall made it a resounding shutout.
McLemore came out wearing a king's robe and trailed by O'Neal, who unveiled a "Shaq-Lemore" jersey. He made it over O'Neal's throne on his second attempt, and O'Neal presented him with a crown.
But moments later, Wall was the real king.
"The slam dunk has returned," said Erving, one of the NBA's most famed dunkers.
Before that, the new format was confusing to fans and the West players themselves, creating a largely silent crowd during their turn. The East had it all figured out, winning the first stage with a passing and dunking display straight out the Harlem Globetrotters, capped by a three-man dunk where Ross threw if off the backboard to Wall, who lobbed it off the overhead shot clock for George to race in and slam it down.
That was just a warm-up for the second round, when Ross, the event's defending champion from Toronto, started things off by edging Lillard with an assist on his dunk from rapper Drake.
Lillard was the first person to compete in three All-Star Saturday events, adding that to Friday's Rising Stars Challenge and Sunday's game to give him the most ambitious itinerary ever.
He started 2 for 2 by following Friday's victory by winning the skills challenge for the second straight year, he and Burke beating Michael Carter-Williams and Victor Oladipo by a tenth of a second.
But Lillard's run was stopped when Belinelli made his final three shots to finish with 19 points, edging him by one to advance to the finals from the West.
"I was happy to just be invited to all of them and be able to compete in them, and I wanted to win at least one. And I won the first one, and then I thought there would be some momentum to continue to try and win all three of them," Lillard said. "But I fell short in the 3-point contest, and as you all saw in the dunk contest, they kind of just outclassed us."
Bradley Beal had 21 points to win the East bracket, then made his final six shots in the finals to tie Belinelli and force a tiebreaker. Belinelli won it by making six straight shots at one point, sweeping his fourth rack.
"I was a little bit nervous at the beginning and I think that I shot like two airballs," Belinelli said.
"But in the end I was focused. I really cared about this trophy."
Bosh, Wilkins and Cash won their second straight shooting stars title, with Bosh making a pair of halfcourt shots.
"I keep asking Coach to let me shoot that shot in the game," Bosh said of Miami's Erik Spoelstra. "He won't let me do it yet, but I think that today will give him confidence if he was watching."
The conferences split $500,000 in winnings for charity.