Written by Nick Hornby, the film is an adaptation of Cheryl Strayed's best-selling 2012 memoir, reported Deadline.
Reese Witherspoon has already signed on to star in the film, which chronicles Strayed's 1,000-mile journey walking the Pacific Crest Trail after divorce, drug abuse and the death of her mother.
Dern will play Witherspoon's on-screen mother in the movie, which will be directed by "Dallas Buyers Club" helmer Jean-Marc Vallee.
Dern most recently starred in the axed HBO series 'Enlightened'.