Brian Rolston and Patrik Elias also scored for the Devils, who have picked up points in seven straight games (6-0-1). Their only blip during the surge was a 3-2 overtime loss at Florida on Jan. 15.
The Devils are trying to climb out of a huge hole. They fell to the bottom of the NHL standings with a 10-29-2 record before the hot streak, a slide that cost coach John MacLean his job just before Christmas.
Panthers coach Peter DeBoer can see a difference in the Devils.
"They have tightened things up as a team," he said. "Their best players, Brodeur and Kovalchuk, are leading the way. We knew coming we were facing a very good team and they showed it."
New Jersey grabbed a 2-0 lead on first-period goals by Kovalchuk and Arnott. Kovalchuk deflected Andy Greene's slapper from the right point at 4:20 for his team-leading 14th goal. The Devils' pressure in the closing seconds paid off as Arnott whipped a backhander past Scott Clemmensen at 19:58.
That was the last shot Clemmensen faced as Jacob Markstrom, recalled Sunday morning from Rochester (AHL), replaced him to start the second period. Markstrom, a 20-year-old from Sweden, made his NHL debut.
Clemmensen yielded two goals on eight shots.
Matthias got Florida back in the game, snapping a shot past Brodeur at 7:22 of the second, but the Devils got the next two goals in the period, both on the power play.
Rolston scored on a shot from the right point at 12:48 to settle things down for the Devils.
"It was a bit of a changeup," Rolston said. "It got into the top corner with a good screen. Our power play didn't look great before that. Sometimes, that's all it takes and you get confidence."
Elias beat Markstrom from the bottom of the right circle at 17:19, a five-on-three tally for his fifth goal in the last seven games.
Kovalchuk assisted on both second-period goals.
In the third, Reasoner popped home a rebound at 5:56 to trim the Devils lead to 4-2 before Arnott closed out the scoring with an empty-netter.
"It's a good feeling in here," Arnott said. "It certainly is a lot more fun winning than losing. I think Jacques has had a big part in that, turning us around."