The Posh had raced to a commanding lead through Kwame Poku, Harrison Burrows, and Ricky Jade Jones and could’ve had another but for a penalty save from Dan Grimshaw.
Despite being down a man for the majority of the second half following Olly Casey’s red card, the Seasiders were able to pull goals back through Kenny Dougall and Sonny Carey, before Ephron Mason-Clark added another for Darren Ferguson’s side.
The visitors took the lead in the 15th minute, after a very quiet start to the game.
Mason-Clark crossed the ball to the back post from the left wing, with Poku arriving to control and finish into the bottom corner past Grimshaw.
Blackpool’s first attempt at goal came just over 10 minutes later.
CJ Hamilton did well to win back possession in the Peterborough box, with the ball coming to Kylian Kouassi- who dragged his effort wide of the post.
Ahead of half time, Ferguson’s side were awarded a penalty, following a trip on Mason-Clark from Matthew Pennington.
The man who won the spot kick stepped up to take it, but was denied by Grimshaw- with the keeper guessing the right way.
Down the other end, Kouassi had another opportunity to level the scores, but couldn’t keep his header down after some good work from Sonny Carey.
A minute into the second half, Neil Critchley’s side had their numbers reduced, with Olly Casey bringing down Ricky Jade Jones on the edge of the box as he was about to run through on goal.
From the resulting free kick, Burrows curled the ball around the wall into the bottom corner to make it 2-0.
A third soon followed, with Jones slotting through the legs of Grimshaw after being played in by Poku.
On the hour mark, Dougall pulled a goal back for the Seasiders, which sparked new life into the game.
That was quickly followed by a strike from Carey, with the midfielder finishing on the rebound to close the gap further.
At the beginning of stoppage time, Peterborough sealed their victory.
Following a mistake at the back from Blackpool, Mason-Clark took the ball around Grimshaw to make it 4-2.
Here’s how the Seasiders performed:
1. How did Blackpool perform against Peterborough United?
We've taken a look at how the Seasiders played against the Posh. Photo: CameraSport - Lee Parker
2. Daniel Grimshaw- 7
Dan Grimshaw stepped up in the first half to keep the game at 1-0. The keeper dove the right way to deny Ephron Mason-Clark from the penalty spot. Unfortunately this didn't impact the final result. Photo: CameraSport - Lee Parker
3. Matthew Pennington- 6
It was a hit and miss afternoon for Matthew Pennington. The defender was at fault for the penalty, with a trip on Mason-Clark, while he was also at fault with some loose passes. There were also positives- including some key defensive contributions. Photo: CameraSport - Lee Parker
4. Olly Casey- 4
Olly Casey was sent off moments into the second half. It was a clumsy challenge from the defender on Ricky Jade Jones, and couldn't have any complaints due to being the last man. Photo: CameraSport - Lee Parker
5. James Husband- 6
James Husband returned to the Seasiders starting line-up for the game against Peterborough. It proved to be a tough afternoon for the defence- especially after going down to 10-men, but the centre back led the team well throughout the tricky periods. Photo: CameraSport - Dave Howarth
6. CJ Hamilton- 6
CJ Hamilton wasn't really given much room to work with throughout the game. There were a couple of good moments from the wing-back before he was subbed off in the second half. Photo: CameraSport - Lee Parker