The York-born centre-half moved to the Black Cats in January from Sheffield United but has found first-team opportunities hard to come by.

And with the return of John Mensah on loan from Lyon and the arrivals of Nedum Onuoha and Titus Bramble at the Stadium of Light, Sunderland boss Steve Bruce has allowed Kilgallon to move to the Championship club.

"Matt can play left-back as well as centre-back," Middlesbrough boss Gordon Strachan told www.mfc.co.uk. "He gives us height as well as experience.

"There's a hunger there. I've explained to him that we're probably looking at a certain position to start with and we'll see how it goes from there."