Barcelona could receive a further €10m in variables for Semedo, 26, taking the total fee to €40m.
€2m will be due after Semedo makes 10 appearances and a further €8m if Wolves qualify for the Europa League.
Semedo has penned a three-year contract with Wolves having the option to add two years to his deal.
Welcome to Wolves, @_nelsonsemedo_!
— Wolves (@Wolves) September 23, 2020
Wolves executive chairman Jeff Shi recognised the importance of the signing.
“It isn’t often that we have the opportunity to sign a world-class player from a world-class club,” Shi said.
Semedo made 126 appearances for Barca after arriving from Benfica in 2017.
The roving full-back is the tenth player from Portugal to join the Wolves first team.
“Last year they did a very good season and it’s a very important team in England, in also Europe,” Semedo said. “I hope this year we can do very good things.
“Coach Nuno is a very good coach. He did very good things here in Wolves, and in other teams too. For sure I’m going to learn a lot from him.”