Antoine Vermette and Dean McAmmond led the way each scoring two goals, while Jason Spezza had a goal and two assists. Dany Heatley, Joe Corvo and Tom Preissing also scored for the Senators (3-4-0).
Ray Emery made 34 saves for his second win of the season, while Martin Brodeur allowed six goals on 26 shots before being replaced by Scott Clemmensen who gave up two goals on 12 shots.
Brian Gionta scored the lone goal for the Devils (4-3-1).
Spezza opened the scoring for the Senators with a power-play goal, just their second of the year with the man advantage, midway through the first period.
Gionta tied the game with just over five minutes remaining in the period as the Devils took advantage of an Ottawa turnover at their own blue-line. But two minutes later, Heatley regained the lead by tipping Tom Preissing's point shot.
The second period opened with a flurry of chances at both ends, but it was the Senators who broke open the game scoring five unanswered goals.
With just one win in their last four games, Senators' fans were desperate for a victory and the 19,166 on hand weren't disappointed.
Vermette picked up his first of the year as he beat Brodeur five-hole and 50 seconds later Corvo, signed during the off-season, jumped into the play and scored from the slot.
Five minutes later Preissing, another defenceman signed during the off-season, scored from the far side boards, and 32 seconds later Vermette picked up his second to make it 6-1 Ottawa.
That put an end to Brodeur's night as Scott Clemmensen was sent in. But he didn't faired much better as Dean McAmmond scored with 57 seconds remaining in the period.
McAmmond picked up his second of the night five minutes into the third frame.
Notes: Ottawa LW Peter Schaefer missed the game due to a hip flexor and LW Denis Hamel was a healthy scratch ... The Devils were without D Alex Brooks (healthy scratch), C Travis Zajac (general soreness) and LW Dan LaCouture (healthy scratch).