Bradford have signed Nathan Doyle on a one-year deal.
Doyle, 25, who enjoyed a highly successful loan spell with City during the 2006/07 season, becomes the ninth signing of the summer at Valley Parade.
"It's an outstanding signing for us," manager Phil Parkinson told the club's official website. "Our recent Ireland tour really gave me a good chance to look at the balance of the side. I just felt we needed a good, versatile, utility-type player and Nathan Doyle was out there.
"We've been working hard recently to bring him in and I think he'll prove to be a great piece of the jigsaw this season.
"Nathan can play all across the back four, as a holding midfield player and in other midfield positions as well. He's also played most of his career at Championship level.
"We'll have to work on his fitness a bit because he hasn't had a pre-season, so he won't feature next week (at Notts County), but we now have a good two-week period to work with him to get him up to speed."