Born in Peru to a Peruvian mother and Argentine father, Nathalie immigrated to Sydney, Australia at 2 years old.
In June 2006, Kelley received her breakout role in the film The Fast and the Furious: Tokyo Drift, the third installment of the Fast and the Furious. In 2010, Kelley played the love interest in the music video for the Bruno Mars song "Just the Way You Are". In August 2011, Kelley signed on in a major recurring role in the second season of the ABC crime drama television series Body of Proof. In 2012, she played a vampire princess in the video clip "Luna Llena" from Puerto Rican reggaeton duo Baby Rasta & Gringo. In 2014 she won a regular role in the Lifetime series Un-Real.