Pettibone allowed just one run on five hits. He struck out three and didn't walk a batter.
The Phillies have now won all three of Pettibone's starts.
"That is what you want to do every time you go out there, give your team a chance to win, and I was able to do that three times," Pettibone said. "I kind of stuck to the same thing, stay aggressive early in the count and let the hitters put the ball in play and have my defense do the rest."
Manager Charlie Manuel lauded the poise of the 22-year-old Pettibone.
"The thing I like is that he can take his fastball and hit both sides of the plate with it," Manuel said. "He made mistakes with breaking balls up and got away with it and was able to put his fastball in a good place."
The Phillies are 14-16, with two more games against the gutted Marlins (8-22) before a seven-game West Coast trip beginning Monday in San Francisco.
Howard homered for the second consecutive night, giving the Phillies a 1-0 lead in the second inning.
Howard's feasting on Marlins pitching is no new phenomenon. This season he is 9 for 17 with two home runs and five RBIs. For his career, he is batting .304 (132 for 434) against the Marlins, with 36 home runs and 99 RBIs in 124 games.
Howard tried something even more impressive than a home run - a triple. He wasn't successful, but he still received cheers after being nailed by second baseman Donovan Solano's relay throw in the third.
Howard's last triple came April 22, 2011, in a 2-0 win over the San Diego Padres.
"At that moment I thought I could pull it out, and I had no shot," Howard said about the triple attempt. "We have to wait until it gets warmer."
The Phillies went up by 2-0 in the second inning when Carlos Ruiz singled, stole second, and scored on Ben Revere's RBI single, more rare occurrences.
Utley's solo home run to right in the third made it 3-0, and there was nothing rare about that. It was Utley's 205th career home run, moving him to sole possession of eighth place on the all-time Phillies list. He had been tied with Dick Allen.
Miami's Solano also did the unexpected, hitting a solo home run in the fourth, his first of the year and third in 401 career at-bats.
Brown added one of his own in the bottom of the inning. It was his second straight game with a home run.
"I think I have always been patient, but I think I am being a little more aggressive now, especially with two strikes," said Brown, who is hitting .382 with three home runs and eight RBIs in his last nine games.
Phillies righthander Mike Adams pitched a scoreless eighth inning, and Jonathan Papelbon added a scoreless ninth for his fifth save.
Contact Marc Narducci at firstname.lastname@example.org. Follow @sjnard on Twitter.