Ripley has signed a three-and-a-half year contract at Deepdale and will be in the PNE squad for Saturday's home clash with Swansea City.
He's made more than 150 first-team appearances in his career, mainly on loan away from Boro.
The 25-year-old was on loan from Accrington Stanley until agreeing the switch to North End, playing 24 times for Stanley in League One.
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Ripley, the son of former Blackburn, Middlesbrough and England winger Stuart Ripley, has had loan spells with Oxford, Bradford, Motherwell, Oldham, Burton, Bury and Accrington.
He also played for Swedish club Ostersunds.
After putting pen to paper on the deal, Ripley said: "I’ve played here before and I have really enjoyed the stadium, it is beautiful.
"The fans are good and I’m looking forward to getting started now.
"It is a special position. Not many people like to be a goalkeeper and not many can be.
"Unfortunately, there is only one position and we all have to fight for it. Declan Rudd is a great goalkeeper and I need to fight for my position."
Ripley is PNE's fourth signing of the January transfer window, following Josh Ginnelly, Jayden Stockley and Brad Potts into the Deepdale arrivals lounge.