Hoffman's winner beat Flyers goalie Michal Neuvirth in the sixth round of the shootout after Philadelphia's Shayne Gostisbehere was stopped by Craig Anderson. Derick Brassard came close to ending it in the fifth round, but his shot clanged off the post.
Brassard, Matt Duchene and Christopher DiDomenico each scored goals for the Senators, who have won back-to-back games to open the month of February after dropping six straight to close out January and eight of their 11 games (3-7-1) last month.
Sean Couturier, Claude Giroux and Nolan Patrick all scored for Philadelphia, but the Flyers were unable to reverse their skid and have dropped four straight (0-3-1) following a season-high-tying four-game winning streak.
Anderson made 33 saves to avoid his 200th career loss and improve to 13-17-5 this season.
Alex Lyon stopped 20 of 23 shots for the Flyers before being replaced by Neuvirth to start the third period. Neuvirth recorded six saves to keep Philadelphia in contention in the final 20-plus minutes.
Duchene's 12th goal of the season opened the scoring 10:53 into the game and Brassard's 13th doubled the Senators' lead at 11:32.
After a scoreless first for the Flyers, Couturier netted his team-leading 27th goal of the campaign 3:53 into the second to give Philadelphia new life. DiDomenico's fourth goal this season restored Ottawa's two-goal lead at the 13:02 mark of the second.
Giroux's 16th goal at 14:15 of the third brought the Flyers within a goal before Patrick's fifth tied the score at 3 in the knick of time with 2.6 seconds left in the game, forcing overtime.
The Senators edged the Flyers 5-4 in their first meeting of the season on Oct. 26. The teams complete their three-game season series Feb. 24 in Ottawa.
Ottawa wraps up a quick two-game trip Sunday in Montreal. Philadelphia begins a stretch of three out of four games on the road Tuesday at Carolina.
--Field Level Media
Ottawa | Philadelphia | |
Ryan Dzingel 2 | Points | Travis Konecny 2 |
Derick Brassard 1 | Goals | Sean Couturier 1 |
Ryan Dzingel 2 | Assists | Travis Konecny 2 |
N/A | Power Play Goals | N/A |
N/A | Short Handed Goals | N/A |
Craig Anderson .917 | Save Percentage | Michal Neuvirth 1.000 |
Craig Anderson 33 | Saves | Alex Lyon 20 |
Team | Shots | Goals | Power Play | Penalty Kill | Penalty Mins | Face Offs Won |
Ottawa | 29 | 4 | 0-2 | 3-3 | 12 | 33 |
Philadelphia | 36 | 3 | 0-3 | 2-2 | 10 | 30 |