Ibrox manager Ally McCoist had admitted an interest in the 31-year-old Scotland midfielder following his decision to turn down a new offer at Cardiff City.
The Scot, who will link up with fellow countrymen Shaun Maloney, James McArthur, Gary Caldwell, Fraser Fyvie and Aaron Taylor-Sinclair at Wigan, said: "As soon as I heard of the interest from Wigan I was keen to discuss coming here. I knew this was the place I wanted to be."
Blackburn's Scotland striker Jordan Rhodes has signed a two-year contract extension. The 24-year-old, who scored 25 goals last season for the Ewood Park outfit, has committed his future to Rovers for the next five years.