Patrick Eaves, Jason Spezza, Dany Heatley and Dean McAmmond scored for Ottawa, which completed a four-game sweep of the season series against Florida. The Senators have won five of their past six games.
Jozef Stumpel and Olli Jokinen scored for Florida.
Florida's Ed Belfour gave up four goals on nine shots, including three goals on the first three shots of the second period. He was pulled for Craig Anderson at 12:01 of the second.
Anderson had 10 saves for Florida. It was his first extensive play for Florida since replacing the injured Alex Auld on Feb. 19. Anderson played less than one minute at Atlanta on March 6.
The Senators took a 2-0 lead on Spezza's power-play goal in the middle period. Joseph Corvo's slap shot from the top of the right circle deflected off Spezza's stick and over Belfour's blocker at 5:26.
Heatley stretched Ottawa'a lead to 3-0 at 9:31 when his shot from the edge of the right circle went over Belfour's blocker. It was Heatley's team-leading 43rd goal.
McAmmond's score gave Ottawa a 4-0 and chased Belfour. He took the puck in the slot and pushed it past Belfour on the stick side.
The Panthers made it 4-1 at 18:22 of the second when Rostislav Olesz's backhanded shot deflected off Stumpel's stick and under Emery's pads. It was Florida's first goal against Ottawa in four games this season. The Panthers last scored against the Senators on Gary Roberts' goal on Nov. 24. The scoreless drought spanned 174 minutes, 53 seconds.
Jokinen made it 4-2 when his backhanded shot slipped past Emery at 11:22 of the third.
Ottawa took a 1-0 lead on Eaves' goal at 2:31 of the first. Eaves picked up a loose puck after a Panthers turnover in the right circle. He took it into the low slot and backhanded it by Belfour on the glove side.
Notes: Panthers centre Chris Gratton, a 13-year veteran, played in his 1,000 NHL game. The 31-year-old was honoured during a pre-game ceremony. Only one other Panther, Martin Gelinas (1,208), has played in more games. ... Belfour has made 25 consecutive starts for Florida. ... Heatley has scored six goals in Ottawa's four wins over Florida this season.