Club captain Jonny Howson has signed up for a seventh season with Boro.
The 34-year-old has put pen to paper on a new one-year contract that will keep him at the club until the end of next season.
The midfielder has clocked up 269 appearances since joining from Norwich City in the summer of 2017 and has been a mainstay of the Boro side since his arrival.
The Yorkshireman has continued to play a key role at the heart of Michael Carrick's midfield, and the Boro Head Coach is delighted to secure his services beyond the end of the current campaign.
"He's a big part of what we do here," said Carrick.
"He's had a good season, he's in great shape, and he's such a great example to the rest of the lads here."
Jonny, Boro's longest serving player after Dael Fry, follows in the footsteps of Tommy Smith by pledging his future to the club.
