Leino deked Stars goalie Kari Lehtonen into trying for a poke check on his shootout attempt, then calmly slid the puck into a wide-open net to collect the game-winner.
The Eastern Conference-leading Flyers, who won for the fourth time in six games, officially wrapped up a playoff spot. They got regulation goals from Jeff Carter and Mike Richards, and Sergei Bobrovsky racked up 27 saves for Philadelphia.
The Stars, scrambling to stay in the Western Conference playoff picture, lost for the third time in four games.
Alex Goligoski and Stephane Robidas got goals for Dallas and Lehtonen ended with 28 saves.