Gionta beat Brent Johnson for his second goal of the game -- his 16th of the season -- to put Montreal up by three 10:47 into the third.
Gionta recorded his first two points of the game 43 seconds apart in the second, scoring on a breakaway at 9:38 before assisting on Scott Gomez's power-play goal that put the Canadiens up 3-1 at 10:21.
"We were initiating the play," Gionta said. "We weren't sitting back and waiting for them to come to us. Against a team like that, so skilled, so offensively talented, you need to initiate the play and get them back on their heels."
"It was a special feeling scoring in the Bell Centre for the Canadiens," said Darche, a 33-year-old Montreal native who played for McGill University. "It was a rush of adrenaline and it was nice because it gave us an extra goal lead. With a team like Pittsburgh you never have too many goals because you know they have the firepower to come back."
"I don't think we played a very good game today as a team, and that's a very disappointing way to lose a match," Penguins coach Dan Bylsma said.
Marc-Andre Fleury, who was replaced by Johnson after Darche's goal, made 24 saves. Johnson stopped three shots.
Pittsburgh, which was outshot 32-21, hadn't played since Monday, when Sidney Crosby recorded his third hat trick of the season in a 5-4 come-from-behind win over Buffalo.
"I think the media has made a big deal about having four days," Bylsma said. "It's not that odd to have that in a normal NHL season."
Scheduled to play in snow-covered Washington on Sunday, the Penguins flew to Newark, N.J. following the game and planned to make the rest of the trip by bus.
Playing as a line, the Canadiens' rookies drew penalties on back-to-back shifts in the second, including Brooks Orpik's interference call at 10:09, moments after Gionta scored on a breakaway to give Montreal a 2-1 lead.
"They created a lot of energy, they created a lot of chances and they weren't a liability at all out there defensively," Gionta said. "I thought they played a great game, especially having three of them together out there."
Gomez made it 3-1 with his eighth goal 12 seconds into the ensuing power play.
Guerin drew Pittsburgh within 3-2 with his 17th goal at 13:57.
Malkin got his 20th goal 16:44 into the third when he came out of the penalty box and drove in on a breakaway to beat Halak.
The game was already tied at 1 just over a minute in after each team scored a disputed goal.
Plekanec opened the scoring 29 seconds in when he fired a shot into a wide-open net after Fleury was upended by Darche after he played a puck behind the goal.
Fleury argued in vain to referee Steve Kozari, who signaled the goal and did not call a penalty on the play.
"I didn't like seeing our goalie on his tail for the goal," Bylsma said.
Dupuis tied it at 1:02 on a play that required a video review. Halak stopped Jordan Staal's shot, but the rebound went in off Dupuis, who drove the crease.
Crosby had a hat trick in a 6-1 win over Montreal on Oct. 28. ... Pittsburgh ended a five-game winning streak against the Canadiens. ... Malkin was serving Guerin's instigator penalty for his fight with White 14:35 into the third. ... Darche, who has five points in nine games with Montreal, made his NHL debut with Columbus in 2000-01 and has also played with Nashville, San Jose and Tampa Bay.