The Wizards, bottom of the Eastern Conference, went on an astonishing 8-0 in the final 8.1 seconds at the Capital One Arena to snatch a dramatic 149-146 victory.
Second-placed Brooklyn (13-9) led by five points with only 10 seconds to play, but suffered a staggering collapse.
Bradley Beal landed a deep shot from beyond the arc after Nets star Kyrie Irving made a pair of free throws, before the Wizards stole the ball as the Nets tried to inbound – Russell Westbrook nailing a three-pointer to put Washington ahead.
Beal then sank two free throws to give the Wizards (4-12) their first win since January 11, bringing a four-game losing streak to a halt.
Wizards coach Brooks said: "It was the first game all year I had a White Claw. I wanted to enjoy it. This is a good feeling.
"I wanted our players to enjoy it. We fought. We fought hard.
"We've done it all year, and the basketball gods gave us a break tonight."
Westbrook (41) and Beal (37) became the first pair of Wizards team-mates to score 37-plus points in a single game since the team moved to Washington in 1974.
Twice in the past two days has a team won in regulation after trailing by five-plus points inside the final 10 seconds – the Portland Trail Blazers on Saturday. It only happened twice in the previous 2,871 days – the Chicago Bulls in 2019 and Boston Celtics in 2016.
Beal scored over 25 points for the 17th straight game to start the season, beating Jordan's mark of 16 from the 1988-89 campaign as the longest such streak since the NBA-ABA merger.
In his latest prolific performance he poured in 32 points as the Wizards overcame the Miami Heat 103-100, despite Russell Westbrook being rested on the second half of a back-to-back.
"It's pretty cool. It's a remarkable achievement," said Beal after Washington improved to 5-13 on the season.
"It's not something you always shoot for but it's amazing just to hear all the stats that we come up with in our game.
"To pass him is always a great feeling, it's something you always put in your accolades, but at the same time it felt even better getting it in a win.
"It was a milestone in a lot of fashions tonight and so I was happy we got the dub overall but to pass Michael means a lot."
The all-time record is held by Wilt Chamberlain, who scored at least 25 points in all 80 games of the 1961-62 regular season.
Asked if he felt emulating that was achievable, Beal responded: "Well if one man did it it's definitely possible. I'm not worried about it."
While Wizards coach Scott Brooks has been amazed by Beal's high-scoring start to the campaign, he was keen to emphasise the other areas of the guard's game that he admires.
"When I think of Brad two things come to mind: winner and toughness. A lot of times just because a guy has a high scoring average they don't want to say that he's an all-round player, that he's tough, but he's a winning basketball player and we're not winning enough right now," said Brooks.
"He's tough. He was fighting for every minute to night. They key to the game was the start of that fourth quarter, we took Brad out, it was a tough decision. We gave him a chance to get his legs and get some rest."
He added: "What he's doing offensively, you don't see it often. James Harden had it in the last few years, but what Brad's doing he's doing it without the ball in his hands throughout the game.
"He scores in so many different ways. The thing he doesn't do is he doesn't post up, but I think he's gonna be eventually able to post up. He does have a good post-up game that we can maybe get going, that's why it's hard to guard him."
Westbrook had 24 assists along with 21 rebounds and 14 points for the Wizards, meaning he will have a triple-double average for the fourth season in his career.
The point guard's 24 assists was an equal career-high, while the Wizards' 50 for the game was a franchise record and the best in NBA history since 1990.
It was also Westbrook's 32nd triple-double of the season, taking him to 178 for his career, only three short of Oscar Robertson's all-time record.
"I've been fortunate to see him for eight years," said Brooks, who coached Westbrook at the Oklahoma City Thunder. "He does a lot of things that are pretty much superhuman at times.
"Point guards don’t do what he does. They're not built that way.
"I used to always say, he's going to go down as the third best point guard ever. I think he's passed one, he's going to go down as the second best. One is obviously Magic [Johnson].
"He's doing MVP-type things every game. He's as high a level as a player this league has ever seen."
Westbrook is averaging 21.8 points per game, 11.3 rebounds per game and 11.2 assists per game this season.
"Personally I feel like I'm the best playmaker in this league because I'm able to do things that nobody else can do," Westbrook said.
"I take pride in playmaking and passing it and making my teammates better. I'm grateful to have a bunch of teammates that make my job so much easier."
That brings the total to six openings around the league, as the Boston Celtics, Indiana Pacers, Orlando Magic and Portland Trail Blazers also are in the midst of the search process.
Brooks' best team during five years in Washington was his first, the 2016-17 side that went 49-33 in the regular season before falling to Boston in a seven-game Eastern Conference semi-finals series.
Washington were not able to build on their young backcourt of John Wall and Bradley Beal, as Wall missed significant time with injury the next few years before moving on to the Houston Rockets.
Brooks went 183-207 (.469) in his five years with the Wizards, who missed the playoffs the last two seasons before bowing out in the first round against the top-seeded Philadelphia 76ers this year.
"We have been committed to taking the proper steps over the last two seasons to develop our young players, bring in pieces to complement Bradley Beal and build a winning environment that will ultimately lead to sustained on-court success," said Wizards general manager Tommy Sheppard.
"Our organization will always be grateful to Scott for his dedication and work both on the court and in the community over the past five years and I personally admire and respect how he helped keep our team together during the unprecedented events of the last 15 months."
The long-time NBA fixture Van Gundy got only one season with Zion Williamson, Lonzo Ball and the Pelicans, going 31-41 and missing the playoffs.
The former Magic, Miami Heat and Detroit Pistons boss could not find a winning formula with a mostly young group in New Orleans, though injuries that kept Ball and Williamson out for extended periods did not help.
Pelicans vice president of basketball operations David Griffin thanked Van Gundy for his "integrity and professionalism" in a statement announcing the move.
"This was a difficult decision as I have tremendous respect for Stan both personally and professionally, but we agreed it is in the best interest of our team to move forward in a different direction," Griffin said.
Hachimura scored 20 points on eight of 12 shooting from the field and grabbed 13 rebounds to play a key role in the Wizards' 122-114 victory over the Philadelphia 76ers in Game 4 of their playoff series.
Though the 23-year-old forward from Japan has started every game he has played for Washington in his two NBA seasons, his performance Monday had his team-mates and head coach Scott Brooks raving.
"He's growing up right in front of our eyes. Sometimes I want these guys to be 27 right now and four seasons of playoff experience, but you get it by going through it," Brooks told reporters.
"He was a big, big part of us on both ends of the floor. He's a multi-defender, he can guard many different types of player, and we need his rebounds. We can't just rely on our point guard getting rebounds.
"He was good on guarding, he was good on making shots. He had a big three and had a big defensive possession not too far from one another."
Hachimura had a pair of key baskets late in the game, capped by a three-pointer off a pass from Bradley Beal that gave Washington a six-point lead over the top-seeded 76ers with 45.8 seconds to play.
"It was a great pass by Brad.... He trusted me and he passed to me, so I had to shoot with confidence," Hachimura said. "That was a big three for sure, especially at this moment.
"I was just trying to be aggressive on both ends, defensively and offensively. As a team I think we played together tonight, and that's why we got a win."
Getting contributions from players beyond the star back-court of Beal and Russell Westbrook is critical to the Wizards' chances, and Hachimura was the player who stepped up for Washington's first win in the series.
After logging 27 and 26 minutes the previous two games, he played 41 Monday, making himself indispensable on both ends of the court.
"For me, we always just want him to be aggressive and accept his challenges on the defensive end," Beal said. "That's when he has a good game, when he's locked in on defence, he's guarding somebody, he's making it tough on them, he's guarding Ben [Simmons], making it tough on him.
"Then he rebounded the ball really well tonight, too. I think him just being engaged in all facets of the game kind of propelled him on the offensive end and boosted his confidence. Once he seen one [shot] go in, he was making them all night."
The key going forward is for Hachimura to play this way more consistently, but his coach liked what he saw in Game 4.
"We're all trying to figure things out, with Rui and with everybody," Brooks said. "This has been a season of figuring it out on the fly at times, but when Rui gets that gear, that's what we need.
"He's had it, it's been choppy at times through some of his unfortunate injuries and safety protocol. He seems to ramp up and then something unfortunate takes place. But he's in a good place."