The series, based on Richard Greener's Locator novels, will chart the exploits of former military policeman Walter Sherman.
TVLine reports that Duncan will play Sherman's partner Leo, who is described as "tough" and a "raw-hide cowboy philosopher".
The actor is known for his role in the 1999 film The Green Mile and has previously played guest parts on Chuck and Two and a Half Men. The Bones spinoff will mark his first regular television role.
Casting is believed to be ongoing for the character of Sherman, who will be introduced in a March episode of Bones.
Sherman was originally intended to be introduced in December, but his appearance was later delayed for "creative reasons".