Blanton (5-4) surrendered the four hits in 7 1/3 innings. He walked three batters and fanned five while throwing 111 pitches.
Philadelphia's runs scored on solo homers by Jimmy Rollins in the first and Chase Utley in the sixth. Rollins had two of the three hits for the Phillies, whose pitchers gave up just three runs during the sweep.
Luis Castillo had two of the four hits for the Mets, who have lost five in a row to the Phillies.
Losing pitcher Johan Santana (9-7) gave up two runs and just three hits in seven innings but was beaten for the fourth time in his last five starts.