Saints were looking for their 22nd successive win at St Mary's, but an horrendous gaffe from former Poland Under-21 international Bialkowski allowed Blackpool to become the first team to take a point from the south coast in 2011.
The visitors looked set to claim all three points until an injury-time equaliser from Rickie Lambert salvaged a 2-2 draw.
Bialkowski, starting his first league match in two years after regular number one Kelvin Davis was ruled out with a groin problem, looked nervous from the outset.
However, top scorer Lambert, back from injury himself, fired Saints ahead on the half-hour before Chris Basham headed an equaliser before half-time.
Bialkowski then gifted the visitors a second when he let Callum McManaman's weak shot dribble through his legs and into the net.
It was reminiscent of Massimo Taibi's howler for Manchester United 12 years ago, coincidentally against Southampton, and his only saving grace is that the error probably came too late to make this year's Christmas blooper DVDs.
But his blushes were in part spared by Lambert, who struck in five minutes of stoppage time to salvage a point for his side.
The omens were not good when Bialkowski's first touch was to spill a cross from Matt Phillips behind for a corner.
The 24-year-old then made an unconventional save with his chest to keep out Ludovic Sylvestre's snapshot.
Southampton set about trying to take the heat off their jittery goalkeeper by going on the attack and Jos Hooiveld headed over, Guly do Prado fizzed the ball across goal and Lambert's shot was just too high.
And their pressure told when Adam Lallana robbed Neal Eardley and played the ball to Jack Cork, who in turn fed Lambert.
The former Blackpool trainee's shot took a big deflection off Craig Cathcart as it flew past Matt Gilks.
Lambert nearly had another four minutes later but this time Gilks managed to block his fierce drive.
That save proved crucial in the 36th minute when the Seasiders grabbed a shock leveller, Basham sneaking in behind the home defence to nod in a cross from McManaman.
And just three minutes later the visitors were inches from taking the lead when Phillips's 20-yard shot hit the foot of the post.
Bialkowski escaped that time, but there was no hiding place for the luckless keeper three minutes after the break.
McManaman went on a mazy run into the area but his shot was tame, and the winger had already turned away to trot back up the pitch.
However, Bialkowski somehow let the ball squirm from his grasp, through his legs and roll over the line as he desperately attempted to claw it back.
Shell-shocked Saints went in search of an equaliser but Gilks saved from Guly, Dean Hammond curled a shot just wide and substitute Steve de Ridder volleyed over.
But in the 93rd minute Frazer Richardson crossed into the area and Lambert powered his header past Gilks to snatch a crucial point.
Southampton 2-2 Blackpool: Match Report - view commentary, squad, and statictics of the game as it happened.
Source: DSG