Dr. Britt Baker made her professional wrestling debut at an International Wrestling Cartel (IWC) event in August 2015, competing alongside Andrew Palace against Dylan Bostic and Ray Lyn in a tag team match, where Baker and Palace were victorious. The following year, Baker appeared on WWE Raw as a jobber, losing to Nia Jax in a squash match. On December 10, 2016, Baker became the inaugural IWC Women’s Champion when she defeated April Sera, Marti Belle, and Sonya Strong in a four-way elimination match.
On September 1, 2018, she competed in a four corner survival match against Madison Rayne, Chelsea Green, and Tessa Blanchard at the All In pay-per-view event, which was won by Blanchard. Baker regained the IWC Women’s Championship by defeating LuFisto and Ray Lyn in a three-way match in October, only to drop it again in November 2018 to Katie Arquette.
On January 2, 2019, it was reported that Baker had signed with new promotion All Elite Wrestling (AEW), being the first female wrestler signed by the promotion. She made her debut for the promotion on May 25 at its inaugural pay-per-view, Double or Nothing, where she defeated Nyla Rose, Kylie Rae, and Awesome Kong in a fatal-four-way match.
On July 13, she competed in a tag team match alongside Riho at Fight for the Fallen, where the two were defeated by Bea Priestley and Shoko Nakajima. Baker suffered a legitimate concussion due to a kick by Priestley during the match, which incited a storyline rivalry between the two. On August 31, Baker competed in the Women’s Casino Battle Royale for an opportunity at the AEW Women’s World Championship at the All Out pre-show, during which she eliminated Shazza McKenzie, ODB, Brandi Rhodes, Mercedes Martinez, and Priestley before she herself was eliminated by Rose. Baker went on to defeat Priestley in singles competition at the Full Gear pre-show on November 9.
At Chris Jericho’s Rock ‘N’ Wrestling Rager at Sea Part Deux: Second Wave, which aired on Dynamite on January 22, 2020, Baker turned heel after she berated commentator Tony Schiavone following her victory over Priscilla Kelly. In May, Baker injured her leg during a tag team match, in which she and Rose went on to defeat Hikaru Shida and Kris Statlander, later stating that she would return in a wrestling role in September at All Out. Baker then began a rivalry with Big Swole, which involved Swole abducting her and tossing her into a trash bin during an episode of Dynamite. At All Out, Baker lost to Big Swole in a Tooth and Nail match, which was taped at her dental office.
In November 2020, Baker began a feud with Thunder Rosa. The two competed against each other at Beach Break in February 2021, where Baker was victorious. That same month, she participated in the AEW Women’s World Championship Eliminator Tournament as part of the U.S. bracket, defeating Madi Wrenkowski in the first round but losing to Rose in the semifinals. Baker’s feud with Rosa concluded the following month after the two competed on the March 17 episode of Dynamite in an unsanctioned Lights Out match in the program’s inaugural women’s main event, during which Rosa defeated Baker.
At Double or Nothing on May 30, Baker defeated Shida to win the AEW Women’s World Championship for the first time. On the premiere episode of Rampage on August 13, Baker held on to the title by defeating Red Velvet, after which she introduced Jamie Hayter as her ally. Baker successfully defended her title for the fifth time when she defeated Tay Conti at Full Gear. At Revolution in March 2022, Baker debuted a new AEW Women’s World Championship belt and retained the title over Rosa. On Dynamite later that month, Baker lost the AEW Women’s World Championship to Rosa in a steel cage match.
Baker participated in the 2022 Owen Hart Foundation Tournament, winning over Maki Itoh in the first round and advancing to the finals by defeating Toni Storm in the semifinal round. At Double or Nothing in May, Baker defeated Ruby Soho to become the tournament’s inaugural female winner.