Howard and Jimmy Rollins each drove in two runs and Victorino homered to help Philadelphia improve the majors' best record to 75-40.
Halladay (15-4) allowed a run and nine hits over 6 1/3 innings and struck out four. The right-hander is 4-0 with a 2.22 ERA since his 6-1 loss at Wrigley Field on July 18, when he was forced out after four innings because of heat exhaustion.
"I would have liked to go a little deeper, but they put some hits together and made us work at it really the whole game," Halladay said. "I felt like my stuff was a lot better tonight than it was last time out and I was able to control things. It's always a grind."
Antonio Bastardo took over for Halladay with Andre Ethier representing the potential tying run, and retired him on an inning-ending double-play grounder with two men on after Ethier got the green light on a 3-0 count.
"I wished that was me," the reigning Cy Young winner said with a grin. "It's a great feeling for a pitcher when guys come in behind you are capable of getting outs. At that point, it's a two-run game, so he's basically saving the game at that point. That was a huge double play."
Michael Stutes and Brad Lidge gave up RBI singles in the eighth, but Lidge hustled after Tony Gwynn Jr.'s bid for a bunt single to the right of the mound with runners at second and third and shoveled the ball to first baseman Howard to preserve the Phillies' one-run lead.
Victorino, appealing a three-game suspension he received Monday from Major League Baseball, gave Ryan Madson an insurance run to work with in the ninth with his 12th homer. Madson got three outs for his 20th save in 21 chances.
"Shane gets a lot of big hits when we need them, and he's done it all year long" Madson said. "He's the type of guy who wants to be up there hitting in those situations. They were coming back in that eighth inning and had some life, and that homer kind of extinguished any kind of life that they did have."
Hiroki Kuroda (7-14) gave up four runs -- three earned -- and nine hits through 6 1/3 innings, making him 2-11 with a 3.16 ERA over his last 14 outings. The right-hander had allowed only three earned runs over 32 innings in his five previous regular-season starts against the Phillies, whom he beat in Game 3 of the 2008 NL Championship Series.
One day after Roy Oswalt returned from a 37-game stint on the disabled list with a 3-1 loss at San Francisco that ended the Phillies' nine-game winning streak, Halladay recorded his eighth win of the season following a Phillies' loss.
Victorino doubled in the first inning on a full count after Kuroda got ahead of him 0-2. Howard drove in Victorino with a two-out infield single that ticked off the top of Kuroda's glove as he tried to make a play on the high chopper.
"They caught a break in the first. Hiro makes a good pitch on Howard and he nubs one off the end of the bat and off the end of his glove," Dodgers manager Don Mattingly said. "But they're a good club. They swung the bats good tonight. We battled, but they just keep coming."
Howard drove in the Phillies' fourth run in the seventh with a double after another double by Victorino. The RBI was Howard's NL-leading 89th, four more than Milwaukee's Prince Fielder and five more than the Dodgers' Matt Kemp.
The Phillies made it 3-0 in the second on a slapstick play. Carlos Ruiz led off with a single and Michael Martinez hit a grounder to first baseman James Loney, who bobbled the ball, possibly thinking about starting a double play. Loney decided to cut his losses and flip to Kuroda covering first, but the ball got past the pitcher.
Kuroda and catcher Rod Barajas both ran it down before Kuroda picked it up. Barajas, realizing that he had left home plate uncovered with Ruiz approaching third, scrambled to get back. So did Ruiz, as third baseman Casey Blake leaped to grab Kuroda's hurried throw from foul territory.
Ruiz then stayed put on a bunt by Halladay that advanced Martinez to second, and Rollins drove in both runners with a double to right-center.
Victorino received his suspension for triggering a bench-clearing incident at San Francisco on Friday night, and prolonging it by shoving an umpire. It all started when Ramon Ramirez hit Victorino in the back with a pitch, moments after Rollins stole second with a six-run lead ... Martinez started at 3B for the Phillies in place of Placido Polanco, whose MRI on Monday in Philadelphia revealed a sports hernia. He will be re-evaluated on Friday. ... The Phillies optioned RHP Scott Mathieson to Triple-A Lehigh Valley after he cleared waivers. Mathieson was designated for assignment on Saturday to clear a roster spot for Oswalt. ... Howard, who averaged 143 RBIs from 2006 through 2009, is 11 away from becoming the first Phillies player to have six straight 100-RBI seasons. He and Hall of Famer Chuck Klein currently are tied for the longest streak in franchise history. ... The Phillies and Dodgers send a pair of lefties to the hill on Tuesday night when Cliff Lee (11-7) faces Ted Lilly (7-11).