Zack Smith and Alexei Kovalev also scored to help the Senators win consecutive games for the first time this season. Brian Elliott stopped 28 shots in his sixth straight start for Ottawa (4-5-1).
"Everyone's chipping in and playing well and I think as a group that's how we're going to have success," Fisher said. "I thought everyone did a good job tonight in all areas of the ice and that was a good feeling."
Bryan McCabe put Florida up 1-0 with a power-play goal midway through the first.
The Senators responded with five straight goals, including three in the second, before Chris Higgins got the Panthers' second goal 6:09 into the third to make it 5-2. Mike Santorelli scored with 56.2 seconds left.
"I don't think we had very much jump and they were firing," said Panthers defenseman Dennis Wideman, who set up McCabe's goal before turning over the puck on another power play early in the second on the play that led to Michalek's short-handed goal which tied it at 1. "I thought they moved the puck really, really well. They broke out well and they came at us and we were just a step behind the whole night."
Tomas Vokoun made 23 saves for Florida, which has lost three of four, including a controversial 3-1 loss in Toronto on Tuesday night.
Michalek drew Ottawa even at 1 with a short-handed goal 5:20 into the second. Chris Kelly stripped the puck from Wideman and went in on a two-on-one with Michalek, who one-timed Kelly's pass for his fourth goal of the season.
Fisher put the Senators ahead 2-1 with his third goal at 13:18 and Smith scored his first of the season 1:31 later to make it 3-1.
Kovalev made it 4-1 with his third goal in two games 1:23 into the third. Michalek and Fisher drew assists on Alfredsson's sixth goal in five games at 3:50.
"We all know that it's a lot easier to play with the lead," Alfredsson said. "That first goal for us short-handed was huge for us to get the momentum."
Florida had allowed 15 goals through its first seven games.
"We hung [Vokoun] out to dry," Wideman said. "He made a lot of big saves but you have a skilled team like that and you give them that many two-on-ones and breakaways and stuff like that, they're going to score. He came up with some big saves but we just kept giving them more and more chances."
Radek Dvorak played his 568th game for the Panthers, moving past Olli Jokinen into second place on the franchise's career list and within five games of Robert Svehla's team record.
McCabe put Florida up 1-0 with his first goal of the season 10:02 in. The veteran defenseman took Dennis Wideman's pass in the top of the slot and drove a slap shot past Elliott inside the right post with Nick Foligno in the penalty box for interfering with Vokoun.
Panthers backup goalie Scott Clemmensen was bowled over by Maple Leafs forward Colton Orr on Toronto's winning goal two nights earlier.
Panthers right winger Michael Frolik, who has two assists in seven games, was a healthy scratch. ... Dvorak, a member of the Panthers' 1996 Stanley Cup finals team as a rookie, played for Florida from 1995 to 2000 and returned in 2007-08. ... Senators center Jason Spezza missed his fourth game in a row because of a groin injury. Spezza, who also missed Ottawa's season opener because of a groin injury, has a goal and four assists in five games.
Copyright by STATS LLC and The Associated Press
Arena: Scotiabank Place Location: Ottawa, Ontario
Referees: Stephen Walkom, Tim Peel Linesmen: Scott Cherrey, Scott Driscoll
Attendance: 16,294 (88.1% full)
Team Stat Comparison
Power Play Goals
Power Play Opportunities
Shots on Goal
Bryan McCabe (1)
(Power Play) Assists: Dennis Wideman, David Booth
Milan Michalek (4)
(Shorthanded) Assist: Chris Kelly
Mike Fisher (3)
Assists: Sergei Gonchar, Daniel Alfredsson
Zack Smith (1)
Assists: Ryan Shannon, Jesse Winchester
Alex Kovalev (3)
Daniel Alfredsson (6)
Assists: Mike Fisher, Milan Michalek
Chris Higgins (1)
Assist: Marty Reasoner
Mike Santorelli (1)
Assists: Cory Stillman, Marty Reasoner