The club has agreed a deal to sign goalkeeper Joe Lumley after his contract with Queens Park Rangers comes to an end this summer.
The 26-year-old agreed terms to join Boro after undergoing a medical at Rockliffe on Wednesday morning.
The goalkeeper is Neil Warnock's first signing of the summer and the Boro boss said: "I'm delighted to have signed Joe. I've always rated him highly and I look forward to him joining us.
"I know he's excited about coming here and he can't wait to play in front of the Riverside crowd."
A former Tottenham Hotspur schoolboy, the young goalkeeper joined QPR as a 16-year-old and has spent his entire professional career with the Loftus Road club.
During the past eight seasons he has had eight loan spells, most recently at Doncaster Rovers last term where he made nine appearances.
Lumley, who was a virtual ever-present for QPR between 2018 and 2020, came on as a substitute at the Riverside in April when he made a string of vital saves to prevent Neil Warnock’s side from victory.
The Harlow-born goalkeeper joins on a two-year contract with the option of a further year.