Highly-rated goalkeeper Connor Ripley has signed a new three-year contract with the club.
The 22-year-old, who has made three senior appearances and featured regularly on the bench in the second half of last season, has been rewarded for his hard work with a new extended deal.
"I'm really pleased with Connor because he has improved a lot since he came here," said Boro Head Coach Karanka.
"He is a very good lad. He's from the Academy and he's training hard, and hopefully he can play more this season because he needs more experience."
Ripley's new deal further enhances the terrific work being done by the club's Academy staff, and Karanka says he is another example to the young players at Boro.
"To play in the first team has to be a reflection of the work," he said.
"The players who are with the first team squad now like Gibbo and Adam Reach are a good example for the Academy players."