The club have beaten off Premier League competition and the highly-rated 23-year-old midfielder joins on a four-year contract.

McNair, a full Northern Ireland international with 20 caps to his name, becomes Boro’s first signing of the summer.

Having begun his career with Manchester United, the youngster made 28 appearances in two years with Sunderland.

The Ballyclare-born man returned from injury to end last season with a string of impressive performances, and four goals in his last five games further demonstrated his eye for goal.

The player’s arrival will add increased competition for places in the team for next season.

Due to the terms of the deal, the fee will remain undisclosed.