A topsy-turvy second half saw the Bantams cancel out the visitors' lead with a 25-yard shot from Omar Daley, before the wheels came off in dramatic fashion.
Midfielder Steven Schumacher was shown his second yellow card on 69 minutes, allowing the Seasiders to reclaim the dominance they had lost.
Andy Morrell restored their lead on 77 minutes, slotting home from close range after being set up by Claus Jorgensen.
Then, as City took off their caretaker manager David Wetherall and replaced him with striker Eddie Johnson in a last ditch bid to claim at least a point, the visitors broke away and Scott Vernon netted in stoppage time.
In between, City had been denied two penalty claims by over-fussy referee Steve Bratt, who brandished nine yellow cards in the game.
Bradford got off to the worst possible start when they conceded a goal from a set piece after just six minutes.
Wes Hoolahan took a corner from the right and the on-loan Robbie Williams nipped in to put a header into the net.
Bradford almost levelled just four minutes later when the hardworking Billy Paynter put a looping header just over the top.
Blackpool were dominating play without really looking as though they would extend their lead and the home side began to edge their way back.
A 25-yard free kick by Marc Bridge-Wilkinson had Blackpool keeper Paul Rachubka well beaten but the ball slammed against a post and rebounded to safety.
That seems to be the sort of luck facing a side desperate to avoid the drop.