Victor Olofsson scored the final result in powerplay at the end of the third period, his third point in as many matches this season.
Philadelphia's only goal came earlier in the same period.
Buffalo, who had had a tough start to the season with double losses to Washington (4-6 and 1-2), took the lead 1-0 at the end of the first period and then switched to the second.
Then came three more goals.
When the Finn Henri Jokiharju put 5-0 just over halfway into the third period, the match was decided.