Guillory and her husband are ex-smokers, she believes in having a healthy lifestyle. She is interested in homoeopathy and natural remedies, saying that when she was a child her mother worked at a health food shop and was hesitant to give antibiotics. Guillory is also a fan of acupuncture. She goes to The Joint Gym on Hollywood Boulevard. She also enjoys Latin and Japanese cuisine and eats at a variety of restaurants in the Los Angeles area.

Guillory describes herself as eclectic and a magpie dresser. She is a fan of the fashion line Moschino, but is not keen on what she describes as "fashion jeans".

Guillory has said that outside acting she "really enjoy[s] writing. Much more than other people enjoy reading it." She has also claimed that the novels Jonathan Livingston Seagull, The Man Who Planted Trees and The Master and Margarita, have played large roles in her life.