Off-season signings Kevin Garnett and Ray Allen both scored 26 points to lead the Celtics, with Allen hitting seven-of-nine from three-point range.
Paul Pierce had 17 points for the Celtics and was named the MVP of the championship series.
"This is unreal. Where we came from a year ago, where I was at, to be here today celebrating with my teammates," Pierce, who was the subject of trade rumours during the off-season, said.
|"We play defence, we're going to win the world championship."|
"I'm just glad Doc [Rivers]... the city of Boston stuck with me during the hard times."
Kobe Bryant, Lakers guard and star player, started quickly but fizzled.
The league MVP had 11 points after the opening quarter but only three free throws in the second period as the Celtics took command.
Bryant finished with 22 points but hit only seven of 22 shots and committed four turnovers in the rout as Los Angeles never closed the gap below 23 points after halftime.
Doc Rivers, Boston's self-effacing coach who credits his players, put his own stamp on the team from the first day it gathered before the season.
"Defence. I said defence,'' Rivers said.
"We play defence, we're going to win the world championship.
"That's what they did. They were phenomenal all year."
Boston, with Hall of Famers Bill Russell and John Havlicek looking on, foiled the Lakers' double-team on Pierce by finding the open man along the perimeter for the shot.
The Celtics' defence did its part, shutting down the Lakers' usually potent offence for much of the game and forcing 19 turnovers.
The home team built an 89-60 lead by the start of the fourth quarter to put the raucous crowd in a party mood.
The Celtics, who celebrated their last title in 1986 when Bird was the MVP, out-rebounded the Lakers at both ends.
At the end of the game, Garnett, who spent 12 seasons with the Minnesota Timberwolves without contending for a title, hugged Russell, who won 11 championships during his 13-year career in Boston.
"I got my own, I got my own," he said in Russell's ear.