It was the 20th shutout of Mason's career and his first in 20 games with the Flyers, who acquired him from the Columbus Blue Jackets in a trade in April.
"There are nights when goaltenders earn a shutout and they do a lot of the work, but tonight was a complete team effort," Mason said. "The guys really worked hard for this win."
"The way we're playing, we're playing as a team, we're following the way we should be playing and we're working hard," said Philadelphia captain Claude Giroux, who assisted on both of Jakub Voracek's second-period goals. "Obviously, when you've got Steve Mason behind us, too, it's easy to play with confidence."
Giroux, who scored his first goal of the season Saturday in a 4-2 win against the Edmonton Oilers, recorded his 300th career point on his linemate's first of the game 28 seconds into the second period. He also assisted on Voracek's second goal of the game, which came on the power play at 10:33 of the second to put the Flyers ahead 3-0.
Philadelphia scored more than two goals for the second game in a row, but only the third time in 17 games this season.
"You get two goals, you know, a quick one to start off the second period, and then to be able to get that elusive third one was definitely big," Mason said.
Craig Anderson stopped 26 shots in his first game since Nov. 3, when he was injured in a goalmouth collision with Dallas Stars rookie Valeri Nichushkin.
"My job is to give the team a chance to win," Anderson said. "It's black and white; there's no gray area there. My job is to give the team an opportunity to win at the end of the night, regardless of what happens during the game, so for me, I've got to look myself in the mirror and say that I've got to be better."
Anderson got the start even though backup goalie Robin Lehner was named the NHL's First Star of the Week on Monday. Lehner led Ottawa to three straight wins while Anderson was sidelined because of a sore neck, posting a 1.33 goals-against average and .958 save percentage.
"I think there are only 20 guys in Philadelphia that are happy with their game tonight, so I don't think there's anyone on our team that should be happy with their game, and Craig's no different than the rest of us," Senators coach Paul MacLean said. "I don't think any of us are happy with how we played. Twenty guys went out there; 20 guys didn't get the job done."
Mason had not blanked an opponent since Mar. 1, 2012, when he made 33 saves for Columbus in a 2-0 win against the Colorado Avalanche.
Ottawa almost ended Mason's shutout bid in the third period but had a goal waved off moments after Schenn scored Philadelphia's fifth goal on a power play at 13:32.
Chris Neil's deflection of Joe Corvo's point shot was disallowed at 14:19 because the Senators right wing made contact with the puck above the level of the crossbar, a ruling that was confirmed by video review.
"My glove was above the crossbar and just even his reaction, I think he knew it right away too," Mason said.
Steve Downie returned to the Flyers' lineup after missing four games because of a concussion. He assisted on Read's goal, his fourth of the season, on a wraparound shot that beat Anderson inside the left post at 16:24 of the first.
Anderson sprawled to make a left-pad save moments later on Voracek's backhand shot on a partial breakaway.
Scott Hartnell got his first assist in 39 games on Voracek's goal early in the second. Hartnell passed behind the net to Voracek, who came out front to stuff the puck inside the right post.
Anderson robbed Giroux of a goal with a spectacular save in the closing seconds of the middle period. The Ottawa goaltender lunged to his right to make a backhand save on Giroux's shot from the left side, stopping the puck in midair with the paddle of his stick.
"I was really shocked, and a little [upset], too, but you've just got to go with it," Giroux said. "Obviously, if it would have been for a big goal, it would have been frustrating, but he made a nice save. There was nothing I could do."
Lecavalier made it 4-0 with his seventh goal at 7:57 of the third.
Senators defenseman Chris Phillips missed the game because of an undisclosed injury.