The highly-rated full-back has moved to The Riverside Stadium on a season-long loan, reuniting with former Swans boss Monk.
“He has settled in well, I was really happy to bring Connor in because he is really going to increase competition," said manager Monk, who joined Middlesbrough from Leeds during the summer.
"It is a step up from where he has been on loans before like at Yeovil and Bristol Rovers, and now it is a higher stage where it is more competitive.
"I think that is the right thing for him, he knows he will have to fight for his chance but I know Connor will take his opportunity when it comes his way.
“He is a fantastic lad with a good mentality, and I hope we can help him develop and then he comes back to Swansea City a better player for the experience."