The 23-year-old left back has signed for Blues for a £1.5million fee and has penned a three-and-a-half year deal at St Andrew's.
"He's a player I've admired for a long time and I made enquiries to see if he had any Scottish blood in him when I had the Scotland job because we would have certainly brought him into the fold with the national team given the displays that we saw up there," Blues boss Alex McCleish has said.