The midfielder, who has one cap for Italy, began his career with Empoli before moving to Udinese and on to Vicarage Road in the summer of 2013.
He scored one goal in 23 appearances in the 2013/14 campaign before being shipped out on loan to Siena, Millwall and Birmingham City.
Speaking to Boro’s website, the 24-year-old said: “I decided to come here this season because Middlesbrough is a big club with a good history and I think this year we can do very well.
“I’m very happy to be here and I’m ready for the start of the new season. I think Middlesbrough are a good team. Last year they were close to going up to the Premier League and I think now this year we must improve.”