The Morrocan international midfielder has signed a two-year contract at Carrow Road in a deal costing the club an initial £500,000.
"I'm delighted to capture a player of Youssef's quality," Canaries boss Nigel Worthington told the clubs official website.
"He's a very good passer of the ball and a hard worker who tackles well.
"He increases our options in midfield and his signing will help to further promote healthy competition for places in the squad, which is important."
