Pettis was born in Arlington, Texas to Michelle and Steven Pettis. She has two older half-siblings.
Pettis was first noticed when her mother entered into an annual cover search held by FortWorthChild, a local parenting magazine. From that she began modeling and acting in commercials; she had an agent and a website from the age of five. She had a co-starring role in the Disney Channel Original Series Cory in the House as the President’s daughter, Sophie Martinez also known as America’s Angel. In this role she was seen in one episode of Hannah Montana. She also starred as Peyton Kelly in the 2007 Disney movie, The Game Plan She portrayed Isabelle Tyler in an episode of The 4400. She was the 2007 Disney Channel Games commentator, and also appeared on Barney and Friendsas Bridget and Jackie, in which she sang, danced and acted. In 2008, she cameoed in Dr. Seuss’ Horton Hears A Who!and she had roles in Mostly Ghostly: Who Let the Ghosts Out?and A Muppet Christmas: Letters to Santa. Pettis also had a small role in Seven Pounds as Lorena, Connie Tepos’ daughter. She is also in Special Agent Oso. She had a role in Free Style as Bailey Bryant with Corbin Bleu. She also made a apperance as herself on the game show “Are You Smarter Than a 5th Grader”.