Farmer went on to establish herself as an international performer, starring in numerous European films, including the dramas More (1969) and Strogoff (1970), as well as multiple Italian giallo films: Dario Argento's Four Flies on Grey Velvet (1971), The Perfume of the Lady in Black (1974), Autopsy (1975), and Lucio Fulci's The Black Cat (1981).

[10][11] In 1962 and 1963, respectively, Farmer guest-starred as Laurie in "The Swingin' Set" and as Joanne Wells in "Boys and Girls" on the sitcom The Donna Reed Show.

She appeared on My Three Sons, Honey West, The Adventures of Ozzie and Harriet, The Outer Limits (March 2, 1964, episode "Second Chance") and The F.B.I.

In 1971, Farmer won a special David di Donatello film award for acting for her performance in The Road to Salina (1970).

Since 1992, she has worked as a sculptor for theatre and opera in France and Italy, and for films such as Oceans, Troy, Charlie and the Chocolate Factory, Marie Antoinette, Five Children and It, The Golden Compass, Pirates of the Caribbean: On Stranger Tides, Wrath of the Titans, Guardians of the Galaxy, and Beauty and the Beast.