The visitors were punished by some clinical finishing from the home side, on a day in which the Iron never really got going.
The away side went into the game unchanged from the FA Cup clash with Chelsea at Stamford Bridge.
Luke Daniels was in between the sticks, and there was a back four in front of him of Jordan Clarke, Murray Wallace, David Mirfin and Scott Laird.
The midfield consisted of Neal Bishop, Jamie Ness, Stephen Dawson and Luke Williams. In attack, Paddy Madden partnered Dutchman Kevin van Veen.
Things got off to the worst possible start for the visitors, when they fell behind to a Tom Aldred header inside of a minute. The Seasiders' defender found room in the box, and planted his header past Daniels and into the corner of the goal, after Danny Philliskirk had delivered from the right.
United almost responded through a Williams strike from 25 yards, but ten minutes after taking the lead the home side doubled their advantage. The Iron were undone by some slick interplay on the edge of the penalty area, which eventually led to Brad Potts being free in the box. The midfielder then made no mistake and flashed the ball past Daniels to put his side in a commanding position.
Robins' side were carrying a threat on the break though, and could have got themselves back in the match on the twenty minute mark, but van Veen could only drag his shot wide from the left hand side of the box.
Then came the Iron's best opportunity of the half. After some good play down the right from Clarke, the full-back whipped a pinpoint cross into the area, which Madden glanced fractionally past Colin Doyle's far post.
Despite the pressure from United, they were punished by the home side once again, just before the half hour, when Potts got on the scoresheet for a second time. There looked to be little danger, but when the ball broke loose in the centre of the park, Potts was clean through on goal, and he finished clinically past Daniels for a second time.
The Iron managed to steady the ship before the interval, but the visitors would have been still very disappointed with the way in which things were at the break.
United began the second period on the front foot, and went close on two occasions inside the first five minutes. Firstly, Bishop had a low strike saved by Doyle, and then Clarke was also denied by the Blackpool ‘keeper after he’d cut in from the right hand side and struck a deflected effort.
Bishop, who’d gone close previously, then glanced a header inches wide of the near post, after Williams had crossed from the left.
However, the bright start was in vain, as the Seasiders added a fourth, ten minutes after the restart. Daniels initially did fantastically well to repel two close range efforts, but he could do nothing about the third, as David Norris fired home after a goalmouth scramble.
The Iron ‘keeper had to be alert shortly after too, when Mark Yeates forced him to acrobatically tip the ball over his crossbar.
United continued to try and find a route back into the game. Ness was the next to have an effort saved by Doyle, as he hit a left-footed shot from twenty yards out. It was a smart save from the Blackpool man, as he had to watch the ball all the way.
The Scot then went for goal from an almost identical position moments later, but again Doyle managed to hold on, as the strike took a heavy bobble.
With ten minutes left to play, Ness found Wallace at the near post, but the defender planted his header just wide of the goal.
The visitors were caught on the break with just over five minutes to go though, when Potts turned provider for Philliskirk. He smashed the ball past Daniels, to put Neil McDonald’s side in dreamland.
United pushed for a late consolation goal, but they failed to find a way past Doyle, on a day to forget for the Iron.
Blackpool: Doyle, White, Aldred, Aimson, Ferguson, McAlister, Potts, Norris (Rivers 75), Yeates (Osayi-Samuel 70), Redshaw, Philliskirk.
Substitutes not used: Letheren, Boyce, Dunne, Oliver, Herron.
Scunthorpe United: Daniels, Clarke (Wiseman 66), Mirfin, Wallace, Laird, Bishop, Dawson, Ness, Williams, Madden, van Veen (Wootton 66).
Substitutes not used: Anyon, Canavan, Townsend, King, Adelakun.
Attendance: 6,004 (340 away).