The news was revealed during a panel with the "AHS" cast at Comic-Con.
Also added to the cast will be "The Normal Heart" cast member Finn Wittrock, Michael Chiklis, John Carroll Lynch and "Hunger Games" actor Wes Bentley.
It has been revealed that Paulson will portray conjoined twins Bette and Dot, with Bates, Peters, Bassett and Conroy as side show performers rescued by Lange's character. Lynch will star as the season's main villain, while Chiklis will play Bates ex-husband and Bassett's current husband.
"American Horror Story: Freak Show" will air in October.