"G put all 20 of us on his back and led us to a big victory," winger Scott Hartnell said, adding that the shot "should be the top one on SportsCenter tonight."
The Flyers scored five third-period goals in the wild win as they moved into third place (a playoff spot) in the Metropolitan Division.
Giroux finished with two goals and two assists - all in the final period.
The Flyers closed the deficit to 3-1 on Jake Voracek's sixth goal in the last six games, a right-circle shot with 15:40 left in regulation. A little more than a minute later, defenseman Braydon Coburn dumped the puck toward the net from the point and it took an odd bounce past goalie Curtis McElhinney, getting the Flyers to within 3-2.
But Hartnell's turnover behind the net led to Blake Comeau's goal with 11:25 remaining to give Columbus a 4-2 lead. Comeau put a weak shot past Steve Mason from out front.
The victory, which also featured three points from Voracek, was the Flyers' eighth straight at home.
The teams will meet again Saturday night, in Ohio.
Mason, playing his first game against his former Columbus teammates, notched the win despite an outing that was far from his best. Afterward, he walked around the locker room and thanked each of his teammates for bailing him out.
"It was a sense of relief, just a good feeling," an emotional Mason said. "I knew I wasn't the main reason we won. I just told the boys I really appreciate everything they did for me tonight. G in particular said you don't have to be the one that's winning us games every single night. He said, 'We're going to come through for you.' They picked one heck of a night to do it for me, and I've got to start being better, and I'll start in practice [Friday]."
Columbus had been 9-0-1 when taking a lead into the third period this season. The Blue Jackets were 36-0-1 when taking a lead into the third since Todd Richards became the head coach.
"They responded in the third period with a great effort from everybody," Flyers coach Craig Berube said. "Our captain came up big."
The Flyers dominated the opening period, outshooting the visitors, 14-4. But they couldn't beat McElhinney, who was playing because former Flyer Sergei Bobrovsky was sidelined by a groin injury that is expected to keep him out of the lineup for about two more weeks.
The Jackets took the lead on Cam Atkinson's shorthanded goal off a two-on-one with 4:44 left in the opening period.
Columbus made it 2-0 with 15:16 to go in the second as Jack Skille converted another two-on-one, blasting a right-circle shot high into the net. With 11 seconds remaining in the second period, Nick Foligno scored from out front, knocking a behind-the-net pass from Jack Johnson past Mason.
Columbus has never beaten the Flyers in regulation at the Wells Fargo Center. The Flyers are 5-0-1 against them on home ice.
The Flyers had been 0-4 in games in which they had tried to get over .500.
That was before the remarkable rally that produced five goals in 14:02.