Boro have completed the permanent signing of Luke Ayling.
The right-back has agreed a two-year contract after a successful loan spell at the Riverside.
Ayling, 32, arrived on loan from Leeds United in January, and quickly established himself as an important figure in the Boro team. He made a total of 19 appearances and registered 8 assists as the Teessiders ended the campaign as one of the Sky Bet Championship’s form teams.
He joins upon the expiry of his contract at Leeds, where he was a promotion winner and made over 250 appearances.
Head Coach Michael Carrick said: “We’re delighted that Luke is staying with us.
“After coming in on loan in January, he settled in very quickly and made a big impact, bringing his character and personality to the group. He knows what it takes to be a success in this league.
“The club has got under his skin and the supporters have really taken to him as well, so it’s great to have him on board permanently.”