Pettibone (2-0) allowed one run and five hits in 6 1/3 innings in his third start filling in for injured lefty John Lannan. The 22-year-old righty lowered his ERA to 3.24 and he's only walked two batters in 16 2/3 innings.
"I want to give my team a chance to win," Pettibone said. "I stuck to the same things, build off each start, stay aggressive."
"With those other guys, there's nothing to worry about," Pettibone said. "You see what they've done in their careers."
Donovan Solano hit a solo homer for the Marlins, who've lost three in a row after winning three straight.
Ricky Nolasco (2-3) gave up four runs and eight hits in six innings.
"I thought Ricky did a nice job, kept us in the game," Marlins manager Mike Redmond said. "He executed his pitches and gave us a chance. We've got to do a better job of putting some runs up. It's tough for our pitching when we're just scoring one run a night. We've got to find a way to put some crooked numbers on the scoreboard."
The Phillies improved to 9-2 combined against the Marlins (8-22) and New York Mets (11-15), but they're 5-14 against other teams.
Pettibone left after allowing a one-out single in the seventh. Antonio Bastardo entered and walked two batters to load the bases. Bastardo then struck out pinch hitter Austin Kearns swinging at a 3-2 pitch out of the strike zone and fanned pinch hitter Matt Diaz looking.
"He's pitched real good," manager Charlie Manuel said of Pettibone. "I like that he can take his fastball and hit both sides of the plate with it."
Howard led off the bottom of the second by lining one out to right for his fifth homer and second in two nights. Two outs later, Carlos Ruiz singled and stole second base. He scored on Ben Revere's single to right for a 2-0 lead.
Utley connected in the third, putting a short, compact swing on a low fastball and driving it out to right for his sixth homer to make it 3-0.
One batter later, Howard ripped a ball into the right-field corner but was thrown out on a headfirst slide trying to stretch the double into a triple. The slow-footed slugger hasn't hit a triple since April 22, 2011.
"He's more patient, he's starting to get good balls to hit and he's staying on the ball better," Manuel said.
Solano hit his first homer of the season out to left-center leading off the fourth to cut it to 3-1.
Brown drove a shot off the right-field foul pole for a 4-1 lead in the bottom half. Brown has homered on consecutive nights and has five this season.
"I think I'm a little more aggressive now," Brown said. "I'm just trying to square balls up and keep it going."
Phillies C Humberto Quintero cleared waivers and reported to Triple-A Lehigh Valley. ... Utley's homer was his 205th, moving him into eighth place on the franchise's all-time list. ... Jimmy Rollins snapped an 0 for 11 slump with a first-inning single. He had been 0 for 12 against Miami this season before the hit. ... Howard has 12 RBIs in his last nine games after driving in just six in first 19 games. ... Nolasco fell to 8-6 vs. the Phillies, including 6-2 at Citizens Bank Park. .. Jose Fernandez (0-2, 4.50) faces Hamels (1-3, 4.78) on Saturday night.