Patterson, 26, is due for a medical with Wrexham ahead of a move that would make him the Welsh club's second most expensive signing in its history, with Phil Parkinson keen to add a new shot-stopper who could feature in Wrexham's Championship opener away to Cardiff City on 17 August.
A product of Sunderland's academy, Patterson made his senior debut in a 2-1 EFL Trophy defeat to Fleetwood Town in 2020-21, before going on to make 169 appearances for the club across two promotion campaigns - including 45 in the Championship in 2024-25, as Sunderland beat Sheffield United in the play-off final at Wembley to reach the Premier League.
He made just one senior top-flight appearance last season after being overtaken by Dutch goalkeeper Robin Roefs, prompting a loan move to Millwall, where he made 16 appearances.
His departure could pave the way for Wrexham to move on from Nigeria international Arthur Okonkwo, whose contract expires at the end of the season, with Wales international Danny Ward also entering the final year of his own deal.
Sunderland's business is not limited to departures. The club have joined the race for Karlsruhe forward Ben Farhat, according to German outlet Badische Neueste Nachrichten, entering a chase that already includes Bournemouth, Lille and Eintracht Frankfurt for the 20-year-old, who is valued at around €10m (£8.6m).
Frankfurt had appeared to be in pole position after agreeing personal terms with the player, but their opening bid was rejected for falling short of Karlsruhe's valuation, opening the door for rivals including Sunderland, Southampton and RB Salzburg to press their own interest.
Born in Germany and of Tunisian descent, Ben Farhat made his senior Karlsruhe debut as a substitute in a 7-0 win over Magdeburg in March 2024 and has since made 33 appearances for the club, scoring nine goals.
He made his senior international bow for Tunisia in friendlies against Haiti and Canada in March 2026, having previously represented the country at Under-20 level, but was left out of Tunisia's World Cup squad this summer after the forward himself judged the tournament had come too soon following a metatarsal injury that had also cost him a place in the 2025 Africa Cup of Nations squad.
Sunderland's interest comes as sporting director Florent Ghisolfi continues to assess young players with development potential, following a summer in which the club have also been credited with interest in Matias Soule, Geny Catamo and Josh Doig.