When she was 10 years old, Rinehart starred as Marta, the second youngest Von Trapp, in a professional production in the Sound of Music in St. Louis, where she was born. This was a precursor to her second role in The Sound of Music in 2013, which was watched by 18 million people on NBC. It was the first full-scale musical made for TV and performed live since 1957.
Rinehart graduated from Lindbergh High School in St. Louis, Missouri, and attended Barnard College, where she majored in sociology and minored in German. As part of the promotion for The Sound of Music Live! she performed one of the songs live in the 2013 Macy's Thanksgiving Day Parade. Rinehart also reunited with the other Von Trapp children in December 2014 at 54 Below for a concert to promote the re-airing of The Sound of Music Live! She has had several other film and television roles, and starred in the Justin Timberlake music video for the song "Mirrors". She appeared as Eve in the film Noah, released on March 28, 2014. In 2016, Rinehart appeared in episodes of Quantico and Blue Bloods, and 2017 in Law & Order: Special Victims Unit and What Would You Do? (ABC News series).
