The Lightning, who entered the game 1-for-26 with the man advantage, converted two of six power-play chances. Ruslan Fedotenko and Dmitry Afanasenkov had the other Tampa Bay goals, while Marc Denis stopped 23 shots.
Ed Belfour made 32 saves in his second start this season for Florida. He had allowed four goals on nine shots in 27 minutes of a 6-0 loss to Atlanta on Oct. 7.
The Panthers got a goal from Stephen Weiss. Florida was 1-for-6 on the power play.
St. Louis put the Lightning up 2-1 on his first goal of the season during a five-on-three power play at 8:30 of the second. The rebound goal came on the fifth shot - including four in-close chances - with the two-man advantage.
Tampa Bay outshot the Panthers 18-5 in the second.
Lecavalier made it 1-0 at 4:20 of the first with a power-play goal. Weiss tied it at one on the power play with 3:19 left in the period.
Fedotenko and Afanasenkov extended Tampa Bay's lead to 4-1 with goals 22 seconds apart midway through the third.
Notes: Florida C Joe Nieuwendyk sat out his third consecutive game with a hip flexor injury. ... Tampa Bay C Andreas Karlsson (groin strain) missed his fourth straight game.