The 21-year-old midfielder signed a four-year deal with the Austrian club.
The Austrian footballer made 67 match appearances, scoring seven goals.
Speaking about the new signing, Wolfsburg sporting director Marcel Schaefer said:
We are delighted that we continue to strengthen our squad with the signing of Xaver Schlager.
He is a young player, who is hungry for success and can now take the next step in his career.
I am really looking forward to Wolfsburg and the challenge to play in the German Bundesliga.
I had a successful time in Salzburg, for which I will always be grateful to the club. But now, the time has come for a change.
Schlager will become Wolfsburg fourth summer.