The motion picture, which will be directed by Sean Durkin, is based on the book Love, Janis, which was also the inspiration for the musical A Night with Janis Joplin, seen on Broadway in 2013 starring Mary Bridget Davies.
Laura Joplin, sister of the late rock singer, authored the book, which, the industry website says, is “built around a series of letters written by the ’60s icon to her Texas family.”
Joplin was 27 when she died of a heroin overdose October 4, 1970. Tony winner Nina Arianda was previously announced to star in the film.
Williams, an Oscar nominee for her performances in Brokeback Mountain, Blue Valentine and My Week with Marilyn, made her Broadway debut opposite Alan Cumming in the most recent revival of Cabaret.
No production timeline for the movie has been announced.