The Championship outfit have been desperately bidding to assemble a squad in time for the start of the new season after being left with a threadbare group at the end of the last campaign.
Manager Jose Riga has since been able to add the likes of Nathan Delfouneso, Tomasz Cywka and Jacob Mellis, and latest arrival Lewis is relishing the opportunity to get some first-team action under his belt.
"I was sat at Cardiff for the last two seasons behind David Marshall, who has done outstanding," he told the club's official website. "I've had to make do with a couple of cup games and the odd league game here and there, and it was pretty frustrating really.
"I knew that I had to get out and play some regular football.
"It's great to come to a club like Blackpool and hopefully make the number one position my own."
The deal includes an option to make the move permanent, but Blackpool will be keen to add a second goalkeeper to their squad as Lewis is ineligible to face his parent club under the terms of the loan.