Newton was raised in Guilford, Connecticut. She is of English descent and began performing musicals and plays at local theaters, and studied at the University of Pennsylvania, where she graduated with a BA in European History.
She moved to New York City and landed several roles in television commercials for such companies as the Olive Garden.
Newton portrayed the character Amanda Tanen in the comedy-drama series Ugly Betty from 2006 to 2010. Newton will star in the upcoming television series Love Bites.
Newton met her husband, Chris Diamantopoulos, in a subway station in New York. It was announced on July 1, 2010 that Newton and Diamantopolous are expecting their first child.