Santon secures move to Newcastle
Newcastle manager Alan Pardew told the Premier League club's website:
"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."
Santon added: "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."
The fee was undisclosed but British media said the defender cost five million pounds.
After making his debut for Inter in 2008/09, Santon played 40 times before spending the second half of last season on loan at Cesena.
Newcastle are also expected to try and secure the signature of Sochaux striker Modibo Maiga on Wednesday before the transfer window closes.
The Magpies have made a good start to the season with seven points from nine and are sixth in the table.