Bolton signs Mills from Leicester
The 25-year old defender has signed a three-year deal with the Trotters for an undisclosed fee after just one season with the Foxes following his move there from Reading last summer.
"Matt is a player who has a high level of experience in the Championship," Coyle told the club's official website.
"We are delighted to have made this acquisition as he adds strength and quality into the mix.
"He is 25-years-old and has already captained teams at this level, so we know what he will bring to the squad both on and off the pitch."