The 24-year-old claimed five league titles and three Swiss Cups during his time with former club Basle, and also had the opportunity to play Champions League and Europa League football.
However, he believes England's top flight represents a whole new test and he is keen to take on the challenge.
He told the Black Cats' official website, www.safc.com: "This is a new challenge for me and I am looking forward to it.
"Playing in Basle, we won everything in Switzerland, and I played in the Champions League and Europa League.
"Now I have a new challenge in England and, for me, it is the best league."