One night after a 3-0 road loss to the Detroit Red Wings, the Panthers took a 3-0 lead after the first period on goals by Smith, defenseman Brian Campbell, and Jokinen and kept rolling.
Smith's 17th goal of the season came 7:40 into the period when he took a pass from Jokinen and took a slap shot that beat Sabres starting goalie Robin Lehner over the glove and went in off the crossbar.
"It seems like we're always kind of on a roll once we get that first one and we were able to pick up the second and third in the first period," Smith said. "That's definitely big and that definitely gave us a little bit of a jump tonight."
Smith hit the empty net with 1:57 left in the third period to complete the scoring.
Video: FLA@BUF: Campbell notches his fifth goal of the year
The Panthers (32-16-6) ended a two-game losing streak. The Sabres (21-27-6) have lost three straight.
The Panthers viewed this as a must-win game after being shut out the night before.
"The guys were disappointed last night," coach Gerard Gallant said. "They played real good [for] two periods in Detroit, but the third period wasn't good and tonight was a big bounce-back game for us. We needed that game tonight because you hate to have those little slides and I thought tonight we came out and played really well."
Campbell made it 2-0 with his fifth goal of the season, a wrist shot that deflected off Sabres defenseman Rasmus Ristolainen's stick and went past Lehner at 10:45. Jokinen's 11th goal of the season with 24.6 seconds left gave Florida a three-goal lead.
"It's definitely a treat to play with [Jokinen]; he does a lot of the little things well," Smith said. "He makes life easy for me and [Vincent Trocheck]. It seems like every game he's coming to play and he's making big plays. It's been awesome playing with him and hopefully the success we've had continues."
Defenseman Alex Petrovic gave Florida a four-goal lead 22 seconds into the second period when his shot from the near boards outside the right circle beat Lehner for his second goal of the season.
Petrovic had a Gordie Howe hat trick with his goal, an assist on Campbell's goal, and three fights against Sabres forward Evander Kane. It was the first time since Jan. 10, 2002 (Jody Shelley and Bob Probert) that two players fought each other three times in one game.
"That was the biggest thing, we came here and got the two points," Petrovic said. "Obviously I didn't think I was going to come in and have three fights, but I think that's just how it goes. I got a good goal there, I got an assist; I got the Gordie Howe hat trick so I'm pretty happy with my output tonight."
Lehner was replaced by Chad Johnson following Petrovic's goal. Lehner made eight saves; Johnson finished with 20.
Video: FLA@BUF: Luongo gets just enough for big save
"No, we didn't [help Lehner], and we didn't help [Johnson], either, when he came in," Sabres defenseman Josh Gorges said. "I think in that situation when they made the goalie change, it has to wake us up as a team. It had nothing to do with our goaltending. We didn't play good enough."
Sabres rookie Sam Reinhart scored power-play goals 3:55 apart in the second period that cut the Panthers lead to 4-2.
Reinhart extended his goal streak to three games 1:09 into the period when he put the rebound of Rasmus Ristolainen's pass off the end boards past Panthers goalie Roberto Luongo. Reinhart's 16th goal of the season came when he redirected a pass by Ryan O'Reilly off his skate and past Luongo. O'Reilly extended his assist streak to four games.
"We felt we kind of handed all those goals to them," Reinhart said. "You give them credit as well, but we could've prevented a lot of them. It was a little rattling, and we were able to make a little bit of a push, but it wasn't enough."
The Sabres had an opportunity to cut the margin to one 1:13 after Reinhart's second goal when forward Daniel Catenacci had a chance in front, but Luongo reached out with his stick and deflected Catenacci's backhand shot into the netting.
"[Luongo] made a huge save when it was 4-2 and that was a turning point in the game and shortly after that Pirri scored the deflection goal," Gallant said. "Buffalo wasn't going to quit. They're a good team. When they made it 4-2, [Luongo] made that big save and that was the difference."
Luongo played in his 906th NHL game, tying him with Glenn Hall for sixth all-time in games played by goalies.
The Panthers regained their four-goal lead when Brandon Pirri scored his 11th of the season at 7:39 and Jaromir Jagr got his 17th of the season, and 739th of his NHL career at 17:53. He is two goals behind Brett Hull for third on the all-time list.
Video: FLA@BUF: Kane scores from tough angle
"Nothing's really secure in this league," Smith said. "[The Sabres] definitely came out with a push and luckily enough [Luongo] made some big saves and we were able to clear some pucks. They had a pretty good push there and they definitely had some opportunities to sneak their way back in the game."
The Sabres got third-period goals by Kane, his 13th goal, and defenseman Mike Weber, his first, to make it 6-4 before Smith's empty-netter.
"I just think we have to have a tougher mentality at home and make this a tougher building, place, environment to play in," Kane said. "I think [we need to] be harder to play against, especially early."
Sabres forward Johan Larsson missed the game with an undisclosed injury he sustained Tuesday morning. Defenseman Jake McCabe replaced him in the lineup.
Panthers forward Garrett Wilson was recalled on Tuesday. He replaced center Aleksander Barkov, who sustained a lower-body injury in Florida's 3-0 loss at the Detroit Red Wings on Monday.
Florida is off until it begins a six-game home stand against the St. Louis Blues on Friday. The Sabres play at the Philadelphia Flyers on Thursday.
"It's nice to go home and have those games," Smith said. "There are definitely some tough opponents that are coming to town, but it's nice to have that home ice advantage and hopefully we can pull some points out of that."
Video: Offense comes to life in Panthers' 7-4 win