Sagal will play Ingrid Jones, a psych patient and love interest for Frank (William H. Macy), reports Variety.
Cox will guest star as Jen Wagner, a famous actress who struggled with alcohol in her past.
The next season of “Shameless” will air 14 episodes in two parts. The first seven episodes begin airing Sept. 9, and the second half of season 9 will premiere on Jan. 20, 2019.