Loken was born in Ghent, New York, the daughter of Rande (née Porath), a model, and Merlin "Chris" Loken, a writer and apple farmer. Both her paternal and maternal grandparents were born in Norway and immigrated to Wisconsin's Norwegian American community. She grew up on her parents' fruit farm in Upstate New York. She has a sister named Tanya.
Kristanna put on 15 pounds of muscle to fit her role of the T-X. Kristanna took a mime class to prepare for her part. Because her character had so few lines, she had to learn to communicate through facial expressions and body gestures.