Antawn Jamison, starting for the suspended World Peace, made the go-ahead basket during a closing 14-3 run for the Lakers, who have won three straight and six of their last seven games.
Howard missed his third consecutive game with a torn labrum in his right shoulder and Gasol, his replacement, injured his right foot with a little more than 4 minutes remaining. He was examined by Nets doctors and diagnosed with a plantar fasciitis strain, and will undergo an MRI exam Wednesday in Boston.
Brook Lopez capitalized on the Lakers' center woes to finish with 30 points and 11 rebounds, but he was the Nets' only offense down the stretch in their fourth loss in six games.
Steve Nash had 17 points and eight assists, and Earl Clark added 14 points and 12 rebounds for the Lakers, who beat the Nets for the 10th straight time. Gasol scored 15 points.
The Lakers improved to 3-0 on the road in February after going 0-7 in January, seizing control in the final minutes without many of the players who were expected to make them a top contender this season.
Bryant's attacking drive and slam between Lopez and Gerald Wallace snapped an 80-all tie, but Lopez answered quickly with a three-point play to give the Nets their last lead with 2:33 to play.
Jamison scored, Bryant drove for another basket and Clark hit a jumper to give the Lakers an 88-83 lead with 1:11 remaining. The Nets couldn't score again, and Nash closed it out with four free throws.
The NBA penalized World Peace for grabbing the Pistons' Brandon Knight around the neck and striking him in the jaw with the knuckles of his mostly open hand on Sunday with 1:43 left in the first half of the Lakers' 98-97 win. The former Ron Artest has been in trouble with the league throughout his career, and Lakers coach Mike D'Antoni, while not disputing the suspension, said he assumed World Peace's history played a role in the league's decision.
The decision on Howard's status belonged to the center, and it was revealed under unusual circumstances.
In what's been a strange and stormy season for the Lakers, D'Antoni pronounced Howard doubtful at the morning shootaround, either unaware that Howard had already decided he wouldn't play or unwilling to announce it. Howard spoke to reporters just minutes later, ruling himself out.
That freed things up for Gasol, one of the top big men in the world but struggling to find his way in D'Antoni's offense and Howard's shadow, to start. He hurt his right foot while defending Lopez with 4:21 remaining, falling to the court without noticeable contact. He stayed in the game after getting attended to by the trainer, but then had to ask out shortly after and returned to the locker room.
Deron Williams scored 11 of his 15 points in the first quarter, leading the Nets to a 24-18 lead. The Nets missed a chance to open things up early in the second against the Lakers' depleted second unit, then Los Angeles surged ahead once its starters returned.
Bryant's follow shot capped a run of eight straight points as the Lakers grabbed a 49-37 advantage with 10.4 seconds to play in the half. Mirza Teletovic followed with a 3-pointer to make it a nine-point game at the break.
Much of the trade focus around Howard during his final season in Orlando centered on the Nets, one of the teams his agent was permitted to negotiate with and the one that was believed to be Howard's preference. The Nets could never put together an attractive enough package and they're happy now with Lopez, headed to his first All-Star game next week.
He scored 12 in the final period, but the Nets had only two other field goals.
NOTES: D'Antoni coached his first game with the Lakers in a 95-90 victory over the Nets on Nov. 20. ... Bryant, who's had high assist totals lately, was asked earlier Tuesday if he would remain in distributing mode in the All-Star game, where he is the career scoring leader. "No, I'm seeing single coverage there. I'm shooting that (expletive)," Bryant said. ... The Nets haven't beaten the Lakers since Nov. 25, 2007.