“It’s exactly what I wanted, and I have a very good feeling. We are back to where this club needs to be, and we want to stay here to write our own history.
“I feel that I’m ready to help the team with my experience but with quality as well.”
Xhaka made 297 appearances at Arsenal, winning two FA Cups and briefly captaining the side before leaving in 2023.
In Germany, Xhaka guided Leverkusen to their first Bundesliga title during his opening season at the club.
However, he expressed a desire to return to the Premier League following Xabi Alonso’s departure as head coach at the end of last season.
Xhaka’s arrival takes Sunderland’s summer spending past the £100m mark.
The Swiss is the club’s eighth summer signing, following the arrivals of Enzo le Fee, Habib Diarra, Noah Sadiki, Reinildo Mandava, Chemsdine Talbi and Simon Adingra.
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