The Black Swan actress is being considered to play the role of Anastasia Steele in the adaptation of the erotic novel, The Sun reports.
The 29-year-old's "girl-next-door charm" is said to have made her the producers' first choice for the female lead.
Harry Potter star Emma Watson and Twilight actress Kristen Stewart have also been linked to the role, while Ryan Gosling and The Vampire Diaries star Ian Somerhalder are rumoured to be in the running to play Christian Grey.
Kelly Marcel will write the Fifty Shades of Grey script, while Michael De Luca and Dana Brunetti will produce the film.
Kunis was named the 'Sexiest Woman Alive' by Esquire magazine this month.
Photo gallery - Fifty Shades of Grey rumoured cast: