Claude Giroux and Scott Hartnell also scored for the Flyers, 7-1-1 in their last nine.
Martin St. Louis scored for the Lightning, who have lost two in a row.
Philadelphia's Michael Leighton, starting his eighth straight game in place of the injured Ray Emery, made 17 saves. Emery has missed 16 games after undergoing abdominal surgery on Dec. 9. Leighton was claimed on waivers from Carolina six days later.
Former Flyers goalie Antero Niittymaki stopped 27 shots for the Lightning.
Tampa Bay failed on four power plays and is 0-for-13 with the man advantage in its last four games.
Giroux put the Flyers ahead with a one-timer from the circle as he fell forward at 13:01 of the first period on a power play. Simon Gagne assisted on the play for his 500th point in his 626th NHL game. Philadelphia teammate Danny Briere posted his 500th point in his 626th career game Wednesday against Toronto.
Hartnell made it 2-0 at 3:36 of the third period, scoring on a breakaway pass from Briere.
After St. Louis scored on a give-and-go with Steven Samkos at 13:05 of the third, Betts put in a rebound at 16:55. He added an empty-net goal with 27 seconds remaining.
NOTES: Tampa Bay's suspended game against the New Jersey Devils on Friday will be resumed Sunday night in Newark, N.J. The Lightning led 3-0 in the second period when lights went out in half the arena. ... The Lightning are 4-1-1 in the second half of back-to-back games. ... Flyers C Mike Richards, who also assisted on Giroux's goal, has 16 points in 16 games against the Lightning.
