Nathalie Kelley was born in Lima, Peru to a Peruvian mother and Argentine father. She moved to Sydney, and dreamed about being an actress when she was 13 years old. She attended North Sydney Girls High School on Sydney's North Shore. When she was 16 she became a salsa dancer, which helped her get the money to finish her education.
The "Miss Latin America competition" also earned her a much-needed $1,000, before she took a year off and went to Brazil. The things Kelley saw there prompted her to shun show business and come home to launch herself into a social science degree at the University of New South Wales. She volunteered with Indigenous Australian youth in the inner-city suburb of Redfern before moving to Los Angeles and eventually becoming a film actress.
In 2005, Charmed executive producers Brad Kern, Aaron Spelling and E. Duke Vincent developed a one-hour pilot for The WB titled Mermaid. Kelley was cast as the series protagonist Nikki, a mermaid who is rescued by a young man when she washes ashore in Miami. The pilot was not picked up as a result of The WB and UPN merging into The CW; the resulting network passed on the show. Kelley has since appeared on both Lone Star and CSI: Crime Scene Investigation. In 2010, Kelley played the love interest in the music video for the Bruno Mars song "Just the Way You Are".
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. Kelley played the role of an Australian schoolgirl attending a Japanese high school. The film was released to largely mixed reviews and made over $158 million worldwide. In March 2008, Kelley appeared in the low-budget drama crime film Loaded alongside Jesse Metcalfe.
In March 2011, Kelley had a small bit role in the retro comedy film Take Me Home Tonight, which starred Topher Grace, Anna Faris and fellow Australian Teresa Palmer. The film was shot in Los Angeles in 2007 but its release was delayed by Universal Pictures for unknown reasons. The following month, Kelley appeared as the protagonist in the low-budget horror film Urban Explorer, which follows a group of four urban explorers who explore an underground world beneath metropolitan Berlin.
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. Kelley appeared in ten episodes and made her final appearance in the episode "Going Viral Part One".
In 2012, she played a vampire princess in the video clip "Luna Llena" from Puerto Rican reggaeton duo Baby Rasta & Gringo. In 2014 she has won regular role in the Lifetime series Un-Real.
In 2017, she recently played as Cristal Flores Carrington in The CW soap opera series Dynasty which was rebooted in October 2017. In June 2018, she left the series after one season and replace by Ana Brenda Contreras as Cristal Jennings in August 2018.