The club have captured talented young midfielder Marcus Browne from Premier League West Ham United in a permanent transfer.
The 21-year-old, who can play on the wing or in the centre of midfield, becomes Jonathan Woodgate’s first outfield signing after Tomas Mejias rejoined the club earlier the summer.
A product of the Hammers youth academy, Browne spent last season on loan at League One Oxford United, scoring nine goals and providing five assists in 44 appearances.
The club have beaten off competition from a host of clubs with the 21-year-old keen to make the switch to Teesside.
A delighted Woodgate said: “Marcus is an exciting, hungry young player who wants to come and play for this football club. He’s just what we need.
“He can play in three different positions and he is quick. I watched a lot of games for Oxford last season and he’s not only the type of player we want here, but he’s also the type we can improve, and he will get better.”