After a goalless first half, Danny Ings' strike gave the Saints the lead before Carroll, marking his 100th appearance for United following his introduction from the bench, made an instant impact as the striker's excellent cross from the right flank was headed home by Jonjo Shelvey.
And, with the clash approaching its latter stages, Federico Fernández stabbed home a late winner for the Magpies in front of the Gallowgate End as Sean Longstaff's strike was parried by goalkeeper Alex McCarthy into the path of the Argentine defender.
"We're buzzing!" Carroll told nufc.co.uk. "It's even better when you go one-nil down and come back to win. It's been tough for the lads after the last couple of games and it's great to get another three points.
"The gaffer changed the formation a bit and put myself and Maxi (Allan Saint-Maximin) up top. He tweaked it slightly and it worked! That's why he is the boss and we listen to him. The tactics he had against Sheffield (United) worked as well.
"That wasn't the greatest game to watch but we got the three points and, today, he has tweaked it when it wasn't working and managed to pull off the win.
"It would be nice to get a cross like that myself but putting it in and getting a goal is all that matters. As soon as we tweaked the formation, we got more joy going forward. They dropped off a lot and we got more into their half and I think it was coming if we got the goal when we did.
"We knew we could get another chance and as soon as Fede (Fernández) got the second one, it was a case of defending. Maxi went off injured so we were down to ten men so it was a hard five minutes at the end.
"I was over the moon (after scoring the second goal)! It couldn't be any better after coming on, setting one up and then we scored a late winner. It's a great feeling for, not just myself, but the team, fans and the manager and everyone associated with the club."
After making his first-team debut in 2006, Carroll's second half appearance against the Saints marked the 30-year-old's 100th appearance for his hometown club as well as reaching a half century of Premier League games for the Magpies.
Steve Bruce's side now sit in tenth place on 22 points and, following an impressive draw against Manchester City and a 2-0 win away at Sheffield United, Carroll - who has provided two assists in his last two league games - praised the squad after a memorable week.
Carroll added: "One hundred games in so many years is a bit mad! I didn't even know I'd played that many but to make that many appearances is great and it's a dream. I've come to hundreds of games myself as a kid watching season after season so playing in the black and white for 100 games is fantastic!
"It's been a great week. The lads, gaffer and staff are all delighted with it. We've been working hard and it's also tough when you play a couple of games within three or four days. Today, the grit and determination we showed to get the three points, especially when you go one-nil down, was great."
