Flatt missed the 2006–2007 ISU Junior Grand Prix season due to injury, but qualified through the regional and sectional qualifying competitions, winning both, and made her senior debut at the 2007 U.S. Championships, where she placed 5th and earned a bye to the 2008 U.S. Championships. Flatt made her international debut as a junior in March 2007 at the International Challenge Cup, which she won. Flatt was often referred to as "Rachael the Rock" and was often called " The Consistency Queen" because of her ability to compete cleanly, landing up to seven triples in a freeskate, including her triple-triple combinations.