Colin Hendry's side fought furiously to defend their lead after Keigan Parker had put them ahead with a 30-yard free-kick in the 23rd minute.
And it seemed as though they would hold out until Ian Breckin finally breached their defences 10 minutes from time with a close-range header.
Blackpool's hard working, tough tacking approach ensured they were hard to break down but, after a scrappy opening five minutes, Forest were soon into their stride.
A clever ball from James Perch gave Jack Lester an early opportunity but the striker for once was off target, chipping his shot over the crossbar from just inside the box.
Nicky Southall, who was a considerable threat against Swansea at the weekend, looked lively again and almost carved an opening for David Johnson with a fizzing cross that Les Pogliacomi claimed bravely at the Forest front-man's feet.
Kris Commons, as ever, was also dangerous on the other flank and almost carved out the opening goal with a teasing ball into the box which Lester and Johnson both challenged for, with Johnson seeming to get the final touch that guided the ball agonisingly on to the crossbar.
But it was the visitors who were to snatch the lead with Parker driving a 30-yard free-kick through the Forest wall and into the bottom corner of the net with Russell Hoult seemingly unsighted.
The goal had come against the run of play but it was superbly executed by the striker who was only included because of the broken leg sustained by Matthew Blinkhorn at the weekend.
Forest almost hit back immediately as Commons prodded a shot against the foot of the post after Lester and Johnson had battled to create an opening.
After the break the theme remained the same, Forest maintained most of the possession but struggled to break Blackpool down and the visitors could have doubled their advantage when Parker turned creator but saw Simon Wiles head weakly at Hoult from an excellent position.
And, eventually, they were made to pay as Forest finally broke down their rearguard as Breckin scrambled a close-range header home from a corner by Commons in the 79th minute.