Dominant in every way.

On a new parquet floor below aging championship banners hung in the rafters two decades back, the Celtics won their 17th NBA title and a first one — at last — for Paul Pierce, Kevin Garnett and Ray Allen — their Big Three for a new generation.

After 22 long years, the NBA has gone green.

Lifted by ear-splitting chants of “Beat L.A.” early and cries of “Seven-teen” in the closing seconds by their adoring crowd, the Celtics concluded a shocking rebound of a season with a stunning 131-92 blowout over the Los Angeles Lakers in Game 6 on Tuesday night.

It means so much more because these are the guys, the Havliceks, the Bill Russells, the Cousys,” Pierce said. “These guys started what’s going on with those banners. They don’t hang up any other banners but championship ones.

“And now I’m a part of it.”

With the outcome assured, Boston fans sang into the night as if they were in a pub on nearby Canal Street. They serenaded the newest champs in this city of champs, and taunted Kobe Bryant and his Lakers, who drowned in a green-and-white wave for 48 minutes.

Garnett scored 26 points with 14 rebounds, Allen scored 26 and Pierce, the Finals MVP who shook off a sprained right knee sustained in Game 1, added 17 as the Celtics, a 24-win team a year ago, wrapped up their first title since 1986.

Rajon Rondo had 21 points, eight assists, seven rebounds and six steals as the Celtics, who built a 23-point halftime lead and obliterated the Lakers, who were trying to become the first team to overcome a 3-1 deficit in the Finals.

They didn’t stand a chance.

Boston’s 39-point win surpassed the NBA record for the biggest margin of victory in a championship clincher; the Celtics beat the Lakers 129-96 in Game 5 of the 1965 NBA Finals.

In the final minute, Pierce doused Celtics coach Doc Rivers with red Gatorade. Owner Wyc Grousbeck, who named his group Banner 17 to leave no doubt about his goal, put an unlit cigar in his mouth — a tribute to Auerbach, the patriarch who had a hand in the franchise’s first 16 titles.

Garnett dropped to the parquet and kissed the leprechaun at center court and then found Russell, the Hall of Famer who taught him the Celtic way, for a long embrace.

“I got my own. I got my own,” Garnett said. “I hope we made you proud.”

“You sure did,” Russell said.

Rivers pulled Pierce, Garnett and Allen with 4:01 left and they shared a group hug with their coach, who was nearly run out of town last season. Rivers lost his father at the beginning of this remarkable run, a season no one expected.

By the time Rivers was handed the Larry O’Brien Trophy, it was June 18 — his late father’s birthday.

When the game clock reached zeros, Rivers reflected on his dad.

“My first thought was what would my dad say,” Rivers said, “and honestly I started laughing because I thought he would probably say, if you knew my dad, ‘It’s about time. What have you been waiting for?’”

It’s was Boston’s first title since the passing of Auerbach, whose presence was the only thing missing on this night. Even Auerbach, who died in 2006, got some satisfaction. Led by Rivers, Auerbach’s beloved team denied Lakers coach Phil Jackson from overtaking him with a 10th championship.

The Boston-Los Angeles rivalry, nothing more than black-and-white footage from the 60s and TV highlights of players wearing short shorts in the 80s to young hoops fans, remains tilted toward the Atlantic Ocean. The Celtics are 9-2 against the Lakers in the Finals.

Boston missed its first crack at closing out the series in Game 5, but the Celtics didn’t miss on their second swing, running the Lakers out of the gym.

Bryant, the regular season MVP, finished with 22 points on 7-of-22 shooting.

He started 4-of-5 from the field and seemed intent on forcing a Game 7. But he missed seven shots in a row and everywhere he went, L.A.’s No. 24 ran smack into a wall of Boston defense as high as the Green Monster.

“They were definitely the best defense I’ve seen the entire playoffs,” Bryant said. “I’ve seen some pretty stiff ones and this was right up there with them. The goal was to win a championship, it wasn’t to win MVP or anything like that, it was to win a championship.”

Garnett and Allen were All-Stars in other cities, stuck in Minnesota and Seattle, respectively, on teams going nowhere. But brought together in trades last summer by Celtics general manager Danny Ainge, a member of the ‘86 Celtics champions, they joined Pierce and formed an unbreakable bond, a trio as tight as the club’s lucky shamrock logo.

They resisted being called The Big Three, a nickname given to Larry Bird, Kevin McHale and Robert Parish two decades ago.

“This is the reason we came here,” Garnett said. “This is the reason we got together, and Danny made it go down. This is it right now.”

With Garnett scoring 17 points and Pierce adding 10, Boston built a 58-35 halftime lead, and unlike Game 2 when they let the Lakers trim a 24-point lead to two in the fourth quarter before recovering, the Celtics never stopped.

They pushed their lead to 31 in the third, and with Boston still up by 29 after three, plastic sheets started going up in the Celtics’ locker room in preparation for a champagne celebration.

No team had to work harder for a championship than these Celtics, who were playing in their record 26th postseason game after being pushed to seven games by Atlanta and Cleveland before taking care of Detroit in six to win the Eastern Conference title.

They entered Game 6 slowed by injuries as Pierce, Kendrick Perkins (shoulder) and Rondo (ankle) were less than 100 percent. There was also uncertainty surrounding Allen, who stayed behind in Los Angeles following Game 5 after his youngest son became ill and was diagnosed with diabetes. The Celtics needed three planes to get back from L.A. and didn’t get home until late Monday night.

But there were no excuses, and just as they had while winning 66 games during the regular season, the Celtics got plenty of help from their bench as P.J. Brown, James Posey, Leon Powe and rookie Glen “Big Baby” Davis came in and contributed.

It was a group effort by this gang in green, which bonded behind Rivers, who borrowed an African word ubuntu (pronounced Ooh-BOON-too) and roughly means “I am, because we are” in English, as the Celtics’ unifying team motto.

The Celtics gave the Lakers a 12-minute crash course of ubuntu in the second quarter.

Boston outscored Los Angeles 34-19, getting 11 field goals on 11 assists. The Celtics toyed with the Lakers, outworking the Western Conference’s best inside and out and showing the same kind of heart that made Boston the center of pro basketball’s universe in the ’60s.

House and Posey made 3-pointers to put the Celtics ahead by 12 points and baskets by Pierce, Garnett and Rondo put Boston ahead by 18.

In the final minute, Garnett floated in the lane, banked in a one-handed runner and was fouled. His free throw made it 56-35, and after Perkins scored, the Celtics ran to the locker room leading by 23.

On his way off the floor, Garnett screamed, “That’s that.”

And so it was.

Game notes
The Lakers had won their previous eight straight Game 6s in the Finals. … Since the Finals began in 1947, 16 have gone seven games, the most recent in 2005 when San Antonio had to go the distance to beat Detroit. … It was the second biggest margin in Finals history behind Chicago’s 96-54 win over Utah in 1998. … The Celtics went 48-7 at home, including 13-1 in the postseason.