Ricardo Rodriguez has been sold by Wolfsburg to AC Milan for €17 million ($19 million).
The 24-year-old fullback is Milan's third new signing this summer.
Capped 45 times by Switzerland, Rodriguez played 24 times in the Bundesliga last season, taking him to a total of 149 outings in Germany's top flight.
Rodriguez thanked his former club for an "unforgettable" five seasons.
"We experienced and achieved a lot together," he told Wolfsburg's official website. "I have developed as a player and as a person, always feeling very comfortable and having won a lot of friends.
"However, now is the time for me to take the next step in my career. Milan are a top international club and a big new challenge for me."