On May 17, 2012, Fliehr signed a developmental contract with World Wrestling Entertainment and was assigned to its developmental territory NXT Wrestling. On August 11, 2012, she was given the name Charlotte. Charlotte made her arena in-ring debut on the January 31 episode of NXT, where she was defeated by Natalya in a dark match. Charlotte made her televised in-ring debut on the July 17 episode of NXT, where she was accompanied by her father to the ring in a winning effort defeating Bayley.
Charlotte made her first appearance on WWE's main roster on the Slammy Awards special episode of Raw on December 8, 2014 where she lost to Natalya. She made a further appearance on the December 30 episode of WWE Main Event, defeating Sasha Banks. Charlotte made her official debut on the July 13, 2015 episode of Raw along with Sasha Banks and Becky Lynch, after Stephanie McMahon called for a "revolution" in the WWE Divas division.