The announcement comes a day before the official title of the new season of the FX horror anthology series will be revealed, during San Diego Comic Con.
Previously announced cast members of the new season include AHS alums Sarah Paulson and Evan Peters, and newcomers Billie Lourd and Billy Eichner.
Murphy previously teased that the upcoming season will be related to the 2016 election.
“Official American Horror Story Season 7 title will be revealed Thursday, July 20,” he tweeted last week. “And suddenly… it will all make sense.”
The project marks Dunham’s first role since wrapping up six seasons of her HBO comedy Girls.
Linda Ge | TV Editor