Davide Santon: "I am really pleased to sign for Newcastle. The chance to play in the Premier League and in front of 50,000 fans at St James' Park was too good to turn down.
"This is an ambitious club who want to move forward and I want to help them achieve that."
Alan Pardew: "We are delighted to bring Davide to Newcastle.
"He is a quality left-back and an established international who also gives us flexibility in defence.
"Davide is a young lad and a great signing for us and I am sure he will adapt to the Premier League very quickly."
Managing director Derek Llambias: "The signing of Davide Santon is a real coup for this club.
"It confirms our commitment to bringing quality players whose best years are ahead of them to St James' Park."