Halladay (1-0) walked one in addition to the six singles. He struck out seven.
Three of the New York hits came in the third inning when Josh Thole, Jose Reyes and Willie Harris singled and loaded the bases. But Halladay struck out David Wright and Ike Davis ground out to end the threat.
Jon Niese (0-1) was roughed up for six runs -- all earned -- and eight hits in four innings in taking the loss.
The Philadelphia offense scored in five innings with Wilson Valdez getting four hits and knocking in three runs. Placido Polanco, who was among three Phillies who had two hits, drove in four more and Raul Ibanez chipped in a two-run home run.
Valdez scored a run and Polanco knocked in the other in the two-run third inning. Polanco drove in two more run in a four-run fourth inning rally and the Phillies made it 8-0 in the fifth on a two-run Valdez double.
Ibanez's first home run of the year came in the seventh and Philadelphia capped the rout with Polanco's RBI groundout in the eighth.