The 28-year-old, who captained the Ewood Park outfit last season, was in talks over a new deal with Rovers but has opted to make the move to Chris Wilder's side.

It is Boro's second new arrival in as many days after Ryan Giles joined on a season-long loan from Premier League side Wolves on Thursday.

Lenihan is set to bring plenty of experience to the Riverside Stadium next campaign with 260 career appearances to his name while he recently returned to the Republic of Ireland side as he featured against Ukraine earlier this month.

Middlesbrough beat a number of Championship clubs to his signature, with the defender out of contract at Blackburn at the end of this month and available on a free transfer.

Boro boss Chris Wilder said: “I've been a huge admirer of Darragh for a long time, in terms of his qualities he brings as a player, as a person, as a competitor, as a warrior, and a leader of men.

“I'm putting a bit on him but I know he can handle it. He's a proper football player and I'm delighted.”

Middlesbrough swoop for Blackburn Rovers captain Darragh Lenihan as Republic of Ireland international signs lengthy contract at Riverside Stadium