Misch (0-1), recalled earlier in the day from Triple-A Buffalo, walked Shane Victorino leading off the sixth and then gave up a long homer to right to Utley - the All-Star second baseman's 26th of the season.
Utley has six homers against the Mets this season, including four at spacious Citi Field.
Rookie left-hander J.A. Happ (10-2) settled down after allowing Omir Santos' RBI single in the second inning that gave the Mets a 1-0 lead.
Happ has won three straight decisions, allowing only one run in each of his last two outings. He scattered eight hits over seven innings, walking two and striking out one. He hasn't given up more than two runs in five straight starts and seven of eight.
Ryan Madson struck out two in the eighth inning, and Brad Lidge got three outs for his 24th save in 32 chances. Lidge earned his 700th major league strikeout when he fanned Daniel Murphy leading off the ninth.
The NL East-leading Phillies bounced back from Friday night's 4-2 loss to the Mets to win for the ninth time in 11 games.
The Mets celebrated the 40th anniversary of their 1969 World Series championship team before the game, but the presence of former stars such as Tom Seaver and Nolan Ryan weren't enough to spark the current club. New York has dropped 13 of 20.
Jeff Francoeur started the Mets' second inning with a double and Fernando Tatis followed with a walk. Happ had a chance to get out of trouble after Murphy grounded into a double play, but Santos singled off the glove of diving third baseman Pedro Feliz to drive in Francoeur.
Redding was sent to the bullpen in July after going 1-3 with a 6.99 ERA in nine starts this season. He got the call Saturday because scheduled starter Livan Hernandez was released earlier this week to make room for reliever Billy Wagner.
Mets manager Jerry Manuel said Redding would be limited to 60-70 pitches, but he was stretched to 81 because of his effectiveness. Redding allowed only a third-inning single to Utley and three walks in five innings, and struck out four.
Misch was brought up to add bullpen depth in case Redding didn't last long. However, it was Misch whose night was short. After Utley's homer, Misch got Ryan Howard to ground out before giving way to Green.
Green struck out Jayson Werth, but consecutive doubles to Raul Ibanez and Feliz pushed the Phillies' lead to 3-1. Carlos Ruiz added a sacrifice fly in the eighth to give Philadelphia a three-run cushion.
NOTES: Victorino and Mets OF Gary Sheffield both barely missed home runs in the first inning as their drives landed just foul. ... The Mets recalled Misch and designated INF Andy Green for assignment before the game. Misch is 0-8 in four major league seasons. ... Utley has three homers and nine RBIs in his last 10 games. ... Misch had a 2.51 ERA in 13 relief appearances with the Mets earlier this season. ... Angel Pagan and Luis Castillo both had two hits off Happ. ... Phillies starters went 26 innings without issuing a walk until Tatis earned a pass in the second. ... The Mets used seven pitchers.