Striker Tommy Conway has become a Boro player after finalising his move from Bristol City.
The 22-year-old joins the club on a four-year contract.
The Scotland international was named Bristol City's Young Player of the Year last season after he bagged 12 goals during the campaign.
Since making his City debut he clocked up almost 100 appearances for the Ashton Gate club, scoring 25 goals in the process.
He made his Scotland debut earlier this summer and was part of Steve Clarke's squad at the Euros last month.
Boro head coach Michael Carrick said: "We're delighted to bring Tommy in. He's a good age, he has great potential and we're really excited to work with him.
"He's already got plenty of Championship experience, and he's a great addition to the squad."
The Taunton-born marksman becomes the club's fifth senior signing of the summer following Luke Ayling, Delano Burgzorg, Aidan Morris and Micah Hamilton through the door.