The drama, which has been penned by Thelma & Louise scribe Callie Khouri, focuses on two musicians - one is already famous, while the other is a rising star.
Britton has now joined the cast as Rayna, the well-known singer, TV Line reports.
She is also expected to sing in the show.
Britton is probably best known for her roles as Tami Taylor in Friday Night Lights and Vivien Harmon in American Horror Story but she has also appeared in shows such as 24, The West Wing and Spin City.
Eric Close recently signed up to play Rayna's husband in Nashville, while Hayden Panettiere has landed the role of the up-and-coming singer.
Other stars who have already joined the cast include Sam Palladio, Powers Boothe, Jonathan Jackson and Robert Wisdom.