The 24-year-old has signed a four-year contrat with a €25million minimum release clause.
Sporting Lisbon have paid a fee of €500,000 for the highly-rated midfielder.
Rinaudo said: “I hope to adapt as quickly as possible so I can give my best to serve the team.
“Physically, I’m in good shape. I hope to play at my best right from the start and to complete the four seasons.”
Rinaudo has previously been linked with a move to Chelsea.
