The youngster recently returned from a temporary switch to Coventry City, where he made 21 appearances for the second tier side, and now joins Rotherham, who celebrated promotion from League One in the summer.
Having been at Wolves for the past 12 years, and made his senior debut in 2019, Giles secured his future with a new contract in December, which will keep him at Molineux until 2025.
Now, the move to South Yorkshire is the latest step in his development, having already impressed at Shrewsbury Town and Coventry, and Giles could make his debut at Middlesbrough on Wednesday evening.