England will open their UEFA Nations League campaign against Spain on September 8, before taking on Switzerland in a friendly on September 11.
"We're delighted with that. I think he deserves it. Given where he was when he first came to the club, he wasn't first choice but worked his way by virtue of his performances and was instrumental really at the back end of last year when I came," Hughes told reporters.
"Some of the saves that he made were match defining saves - the saves that enable you to protect results and gain points and he did that on any number of occasions in the latter part of last year.
"That's the sign of a top keeper when you need him to step up and protect the result for you and Alex did that on numerous occasions."
McCarthy made three appearances for England's Under-21 team between 2010 and 2011.