Travis Zajac had the other goal for New Jersey (29-24-13), which won for the fifth in seven games to move within two points of the third-place Flyers in the tightly bunched Metropolitan Division.
Nicklas Grossman scored for the Flyers (33-25-7), who are 7-2-1 in their last 10 games. Philadelphia had a potential tying goal by Scott Hartnell disallowed by officials with 40.1 seconds remaining because it was determined that Hartnell pushed goalie Martin Brodeur into the net.
Marek Zidlicky set up Jagr for the decisive goal with a backhanded pass from behind the net. Jagr lifted it off goalie Steve Mason and just inside the near post from close range to put New Jersey ahead 2-1 with 12:18 left.