In May 2013, she signed a contract with WWE and was assigned to WWE Performance Center and developmental brand NXT in Orlando, Florida. Bliss made her main roster debut on the SmackDown brand, eventually becoming SmackDown Women's Champion as well as the first competitor to hold the title twice. She was transferred to the Raw brand in April 2017 and won the Raw Women's Championship later that month, becoming the first woman to have won both the Raw and SmackDown Women's titles and overall a four-time champion in WWE. In February 2018, she won the first-ever women's Elimination Chamber match.

Kaufman was signed by WWE in May 2013 and reported to WWE's developmental territory NXT. On the July 24 episode of NXT (which was taped on June 20), she made her first televised appearance, congratulating the inaugural NXT Women's Champion Paige. In August, she was added to WWE.com's NXT roster page and assigned the ring name Alexa Bliss. She acted as an unnamed ring announcer for the November 20 episode of NXT. Her first televised appearance on the main roster came at WrestleMania XXX on April 6, 2014, when she played a part in Triple H's entrance. She made her televised in-ring debut on the May 8 episode of NXT, playing a glitter fairy gimmick, competing in a tournament for the vacant NXT Women's Championship. She defeated former Divas Champion Alicia Fox in the first round, but lost to Charlotte in the semi-finals.

After a hiatus due to a legitimate injury, Bliss returned on the March 11, 2015 episode of NXT, where she defeated Carmella. The following week on NXT, she defeated NXT Women's Champion Sasha Banks by countout in a non-title match, which led to Bliss being granted a title match against Banks on the March 25 episode of NXT, which she lost. On the May 13 episode of NXT, Bliss defeated Carmella after the NXT Tag Team Champions Buddy Murphy and Wesley Blake set up a distraction. On May 20 at NXT TakeOver: Unstoppable, Bliss helped Blake and Murphy retain the NXT Tag Team Championship against Colin Cassady and Enzo Amore, forming an alliance with them and turning into a villainess character in the process. On the July 29 episode of NXT, Bliss helped Blake and Murphy retain the NXT Tag Team Championship against The Vaudevillians (Aiden English and Simon Gotch) and slapped both English and Gotch after the match. The Vaudevillians were granted a rematch for the NXT Tag Team Championship against Blake and Murphy at NXT TakeOver: Brooklyn on August 22, which they won after Blue Pants stopped Bliss from providing a distraction during the match. This led to a match between the two, where Bliss would go on to defeat Blue Pants in a singles match on the September 2 episode of NXT.

On July 19, Bliss was drafted to the SmackDown brand as part of the 2016 WWE draft. She made her main roster debut on the July 26 episode of SmackDown Live in a segment involving the brand's women's division. Bliss achieved her first victory on the main roster by defeating Becky Lynch on the August 9 episode of SmackDown Live. On August 21 at SummerSlam, she teamed with Natalya and Nikki Bella in a winning effort against Lynch, Carmella and Naomi. On September 11 at Backlash, Bliss competed in a six-pack elimination challenge to determine the inaugural SmackDown Women's Champion, in which she was unsuccessful and was won by Becky Lynch.

On July 24, 2017, it was announced that Bliss would be joining the seventh season of Total Divas. She is a fan of cosplay which has inspired many of her wrestling atires such as Freddy Krueger, Harley Quinn, Iron Man, The Riddler, Supergirl and Chucky.