Saturday's game marked the halfway mark of the season for Ottawa, which continue to chase a playoff spot.
Ottawa hoped to redeem itself after a poor finish to Friday's 5-0 loss in Boston. The Senators got off to a strong start and managed to play well enough through 60 minutes to hold off the Bruins to the delight of the 20,500 on hand in Ottawa
Ryan scored the winner at 15:25 of the third after forcing a turnover at the Ottawa blue-line and breaking in alone, beating Johnson with a high backhand.
Smith was called for a faceoff violation with two minutes left to play, leaving Ottawa shorthanded. Still, the Senators managed to hold off the hard-pressing Bruins and earn the win.
Earlier, the Senators caught a break when what would have been Iginla's second of the night was reviewed and ruled to be kicked in, keeping the game tied 3-3.
Ottawa opened the scoring at the seven-minute mark of the first as Wiercioch jumped into the play to grab a rebound and beat Rask through the legs.
The Bruins tied the game on Paille's fourth of the season as he sidestepped Erik Karlsson along the sideboards and beat Anderson cleanly.
Conacher made it 2-1 for the Senators when he tipped a Kyle Turris backhand.
The Senators made it 3-1 just 29 seconds into the second on Smith's short-handed goal. It also marked the end of Rask's night.
Anderson made a number of good saves through the second, but had no chance on Iginla's 12th of the season as he was left all alone at the side of the net for an easy tap in.
Warsofsky, with his first in the NHL, tied it 3-3 at the six-minute mark of the third with a shot from the side boards.
Notes: C Jason Spezza and D Chris Phillips missed the game with a lower body injury. In Spezza and Phillips' absence Kyle Turris and Erik Karlsson wore an 'A'. D Eric Gryba was a healthy scratch for the Senators. … The Bruins announced D Dennis Seidenberg will miss the remainder of the season with a knee injury. D Zdeno Chara was a late scratch and is listed as day-to-day. The Bruins were also without C Carl Soderberg. D Zach Trotman was recalled on an emergency basis and made his NHL debut.