The Bruins beat the Panthers for the second time in six days, including a 4-1 loss on Tuesday in Boston.
"They're still a benchmark," Panthers coach Peter Horachek said. "They're still the team that we have to gauge ourselves by. That's a message to our guys, that's where we need to be."
The Bruins tied it at 1 on a power-play goal by Meszaros. His slap shot from above the right circle got past Luongo at 9:58. It was the first goal Luongo gave up in nearly 90 minutes since rejoining the Panthers for Friday's 2-0 win against Buffalo.
Meszaros made his Bruins debut after being acquired from Philadelphia last Wednesday.
"It was good to go out there and play. Overall, I felt pretty good and the two points is huge," Meszaros said.
The Panthers took a 1-0 lead on Hayes' first goal at the 7-minute mark of the second. Nick Bjugstad shot from the right side and Johnson made the block, but Hayes grabbed the rebound and wristed it into the open net on the stick side.
The Bruins went after Luongo from the start. He faced 27 shots in the first two periods, with at least three hitting the post, including a deflection off the skate of Panthers defenseman Brian Campbell early in the second that glanced off the iron.
"You have to give (the Bruins) credit," Luongo said. "They came out hard in the third and they created some scoring chances. I would have liked to have made a few more saves there at least to keep it a one-goal game, but they have some good players there who can make some plays.
"Things kind of fell apart a little bit in the third."
NOTES: Bruins F Daniel Paille left with an upper-body injury after being hit by Ed Jovanovski along the boards at 3:06 of the first and did not return. ... Corey Potter, claimed off waivers by Boston from Edmonton on Wednesday, was a healthy scratch. ... Bjugstad has five points the past six games for the Panthers. ... Panthers D Erik Gudbranson left in the third period with a lower-body injury and did not return.