Loken was born in Ghent, New York. Having been a model since the age of fifteen, Loken had her breakthrough acting role as the deadly T-X machine in the 2003 film Terminator 3: Rise of the Machines, co-starring David Andrews, Earl Boen, Eric Ritter, and Carolyn Hennesy. Prior to that, she was a regular on a number of television series, including Unhappily Ever After (co-starring with Nikki Cox), Pensacola: Wings of Gold, and Mortal Kombat: Conquest.