United signed the 25-year-old right-back in a £12.7million deal from Torino on the weekend and Materazzi is tipping him to shine in the Premier League.
"Darmian plays very well. In the World Cup, he was maybe not the best player but more or less did a good job," Materazzi told Goal.com.
Materazzi also claimed that Darmian is the best wing-back in Italy.
He added: "He has a big opportunity with Manchester United to grow because he's a good player, he's playing for the national team and now for United.
"I think he's the best wing-back in Italy."