Two goals in six minutes just before the break turned this game on its head.
Barnet had taken a shock early lead through Adam Birchall, but, by the interval, they found themselves behind.
And Rochdale shrugged off a sluggish first-half performance to turn on the style in the second half, running out comfortable winners and condemning the Bees to their third straight defeat of the season.
Barnet, playing in their change strip of white shirts and red shorts, made one change from the side that lost to Brighton, and that was enforced, with Michael Leary coming in for the suspended Kenny Gillet.
Leary took his place in the centre of defence, with the versatile Joe Devera filling in at left-back.
The Bees took less than two minutes to strike. A long ball into the box was not cleared and it fell to Adam Birchall, who took it down, before steering it into the far corner from a tight angle just inside the six-yard box with his left foot. It was a superb finish from the Barnet striker.
Dale's Adam Rundle skimmed the bar with a cross a few minutes later, as the stunned home side looked to get back into it.
Albert Adomah went on a typically brilliant run on 15 minutes, carving through the home defence before slipping in Luke Medley, but the new signing was offside.
The hosts were struggling to make an impact, with the Bees enjoying plenty of possession. It was certainly not the start fancied Rochdale were hoping for.
Barnet should have doubled their lead on 28 minutes. A Medley cross to the near post was only cleared into the path of Joe Tabiri, but, with time and space, the youngster lashed it into the side netting. He should have at least hit the target, the teenager lacking a little composure on this occasion.
Birchall also had a crack a few minutes later, though his shot from long distance was always going over and keeper Sam Russell looked to have had it covered.
Dale manager Keith Hill called for patience from home fans in his programme notes, but they were showing little, with some already voicing their disapproval.
But, with their first shot of the game, the hosts struck on 38 minutes. Rundle took possession from a throw-in and headed towards goal. After squaring the ball to Gary Jones, the ball came back to him in a good position 12 yards out, and the striker buried it under Rob Beckwith in a flash.
It was cruel on the Bees, as they had appeared to be more than comfortable and looking good to take a one-goal advantage into the half-time break.
But it was to get even worse for Barnet. With one minute of the half remaining, Chris Dagnall volleyed Rochdale in front from the angle of the box, the striker latching on to a Clark Keltie charge down, which looked suspiciously like handball. Beckwith managed to push his shot on to the post, but it finished in the net rather than bouncing to safety.
It was an amazing turnaround, Dale having scored from their only two shots of the half.
The home side started the second half on top, but there were no clear-cut chances for either side in the opening exchanges.
The first real shot came from Dale sub Ciaran Toner, but he was off target.
Just after the hour, Medley broke down the left after Neal Bishop had won the ball. Medley chose to shoot early and his low drive was pushed to safety by Russell.
At the other end, Jon Shaw got his head to a cross from the left, but it was just too high for him and he could not keep the ball down.
Rochdale were now the side looking in control and it was no surprise when they struck a third with 18 minutes to go. A long Russell clearance dropped perfectly for Shaw and he cracked home a superb volley from just inside the box. It was another brilliant finish.
Beckwith did well to turn over an Adam Le Fondre snapshot on the turn, as Dale looked to kill off their visitors. Keltie was next to have a go, his back-post effort finishing just over and wide.
It was now all Rochdale, the Bees struggling to get out of their own half. Le Fondre also saw Carew stop his stooping header on the line.
Tabiri saw a rare chance held by Russell, but most of the action was at the other end.
Le Fondre turned provider on 82 minutes, rolling the ball into the path of Jones, but the veteran saw his first-time shot just clear the bar.
Sub Le Fondre was now running rings round the visitors. He brilliantly turned Leary, but Beckwith blocked his close-range effort.
BARNET (4-4-2): Beckwith; Carew, Yakubu, Leary, Devera; Adomah, Porter (St Aimie 68), Bishop, Tabiri; Birchall (Hart 79), Medley. Subs not used: Harrison, Thomas, Akurang.
Attendance: 2,442.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here