The 26-year-old has agreed a four-year contract, running until the end of the 2029-30 season, and becomes Phil Parkinson’s third summer signing.
Patterson made 169 competitive appearances during his 17-year association with Sunderland, helping the club secure two play-off promotions.
“Wrexham really suits me in terms of what I want to do in my career, so it feels like a perfect fit,” Patterson told the club website.
“I've seen the journey that the Club's been on and it's really exciting to now be part of it. I want to play in the Premier League with Wrexham, and I think everything is in place and ready for the Club to do that.
“I’m really looking forward to playing in front of our fans, pushing up the league, and getting this Football Club to where it deserves to be.”
A product of the academy, he made his senior debut against Fleetwood Town in November 2020 under Parkinson.
Patterson was a regular in Sunderland’s Championship side, featuring in their 2025 play-off final victory over Sheffield United.
He spent the second half of last season on loan at Millwall, making 16 appearances and helping them finish third.