Barr started her acting career in 2003 (age 7) with Disney Channel Original Movie Right On Track.

She was praised for her work ethic and maturity on set. Producer Jason Nacey of The Doorstep stated that she “stuck out like a sore thumb”, among other actors her age, after booking the lead role as a walk-in on the final round of auditions. Her roles in 2005's The Doorstep, 2006's Unrest and 2007's The Last Sin Eater and The Dance established her as a serious, mature-beyond-her-years Actress.

Under the direction of manager/producer Jean-Marc Barr, Barr joined with Aaron Hurt to form Shrink the Giant in the fall of 2010. They immediately began recording an album.

Barr's fame was established in 2011 by playing Maysilee Donner in The Hunger Games: Second Quarter Quell. Fans around the world immediately accepted and embraced her as the face of Maysilee, and a part of The Hunger Games "fandom."

November 16, 2012 marked the release of the Summit Land Conservancy's 2nd Edition book, Summit County: Witness, which used a photograph taken by Barr as the cover image. The same photograph was also printed in Photographer's Forum "Best of High School and College Photography: 2012," earlier in the year, and accepted into the Springville Art Show, of Springville Utah, the previous year.

Shrink the Giant also recently completed their second album "Faceless". It was released worldwide on December 4, 2014 in both digital download and CD format.