Mika Zibanejad and Filip Chytil also scored for the Metropolitan Division-leading Rangers, who have won six of eight.
"I was really proud of our group tonight," Rangers coach Gerard Gallant said. "We competed, we played well and everybody chipped in."
Oskar Lindblom and Cam York scored for the Flyers, who dropped their seventh straight. Carter Hart made 24 saves.
"We know that we need a win and you start playing to think about only that result and quite often you forget about that one little thing you have to do right at that moment," interim coach Mike Yeo said. "It's very challenging when you're dealing with the stress and emotion of going through a losing streak like this. You have to make sure you continue to stay focused on the process."
Gallant returned to the bench for the Rangers after missing the last two games due to health and safety protocols. New York finished an 11-day, five-game road trip 3-2.
Igor Shesterkin, coming off of consecutive shutout victories, made 26 saves for the Rangers.
Kreider scored on a deflection from the slot after Fox's pass from long range. Both Kreider and Fox were named to the Feb. 5 All-Star Game on Thursday, marking the first time since 2012 that the Rangers will have multiple players there.
"He's definitely been a dominant player this year," Fox said of Kreider. "When we need him, he steps up."
Kreider, who entered tied for fourth in the NHL in goals, netted his team-leading 24th.
"He's playing with a lot of confidence and things are going in for him," Gallant said.
Fox upped his assist total to 34 with his second of the contest.
The Rangers are 6-1 against Metro opponents and 16-3 versus the Eastern Conference.
York, playing in his eighth career game, scored his first NHL goal with a slap shot from long range that knuckled past Shesterkin and gave the Flyers a 2-1 lead with 9:49 left.
"It felt really good," York said. "Just wanted to get it on net, and luckily for me it went in."
Chytil answered 37 seconds later by finishing from in close after a pretty tic-tac-toe passing play with Ryan Strome and Artemi Panarin.
"Great feeling, for me personally and also for the team," Chytil said.
Zibanejad got the Rangers on the board with a one-timed slap shot from the circle on the power play that beat Hart over the right shoulder 5:54 into the contest. Fox set up the tally for Zibanejad, who has 18 points during a seven-game point streak against Philadelphia.
The Flyers didn't get their first shot on goal until a little more than nine minutes left in the first, but they got on the board soon after when Lindblom finished a rebound from in close. It ended Shesterkin's shutout streak at 133 minutes, 41 seconds.
New York nearly took the lead with 3:43 left in the period, but Flyers defenseman Keith Yandle batted the puck off the goal line after Chytil's backhander got behind Hart.
Rangers: Forwards Alexis Lafrenire and Barclay Goodrow didn't play due to health and safety protocols. Lafrenire was sidelined for his second straight game and Goodrow his third in a row. Forwards Julien Gauthier and Ryan Reaves returned to the lineup after being out for the last three due to health and safety protocols.
Flyers: D Rasmus Ristolainen cleared health and safety protocols after missing a game but didn't play as he regains strength. ... C Derick Brassard (hip) has missed 14 of the last 15 contests. He is not skating but remains day to day, Yeo said. ... C Sean Couturier (upper body) and D Ryan Ellis (lower body) received treatment on Saturday, but there is no timetable for their return. Couturier has missed 10 in a row. Ellis, out since Nov. 13, has played in just four contests this season.
Rangers: Return home to face Toronto on Wednesday.
Flyers: Play the first of two games in two nights against the Islanders on Monday night in New York.