Jerry Yates netted a brace, striking within the first minute of play and adding a penalty after the break. Luke Garbutt wrapped up three points for Blackpool on the hour mark.
But defeat was far from on the cards when Joe Ward took the game to 1-1 in first-half stoppage time, leaving Posh manager Ferguson disappointed about the squandered opportunity.
Speaking after the game, he said: "We started off very poorly after conceding in the first minute and it clearly affected us.
"The goal gave them a lot of confidence and they were on the front foot. They were well on top for the first 15-20 minutes and the game could have got away from us.
"We got a lifeline on half-time. To be honest I was thinking I would be OK going in 1-0 down.
"We are conceding too many goals and making too many individual and team mistakes and we have to get back to the basics.
"We have to stop conceding soft goals. My keeper (Christy Pym, who failed to clear from a corner) is a great signing but he’s having a bad patch at the moment and I have to stick by him.
"Twice we have played Blackpool this season and twice they have deserved to win, they are one of the best teams."
Yates got Blackpool off to a flyer when he drilled home from 20 yards out for his 15th goal of the campaign. From there, Blackpool commanded a spell of dominance, with shots from Demetri Mitchell and Yates were off target.
Sam Szmodics blasted wide for Peterborough in the 24th minute, before Siriki Dembele had a shot blocked.
Seconds before half-time, Ward volleyed into the bottom corner to level for Posh.
Yates restored Blackpool’s lead with a 52nd-minute penalty after Jordan Thorniley’s strike was handled by Ethan Hamilton, and Garbutt wrapped up the points with a deflected strike following a short corner in the 58th minute.
Boss Darren Ferguson was booked for ranting at referee Bobby Madley after he waved away penalty shouts when Szmodics went down on 82 minutes.
The result leaves Peterborough three points behind leaders Hull with a game in hand and two clear of third-placed Sunderland, having played a match more than the Black Cats.