Early career Baumgardner made her professional debut against Britain Hart on March 4, 2017. She won the fight by a first-round technical knockout. Baumgardner notched her second win as a professional 22 days later, needing just 63 seconds to stop Wendy Toney. Her remaining two fights of the year ended just as fast, as she stopped Lashanda Tabron in 57 seconds on June 30, 2017, and Brittney Artis in 36 seconds on August 25, 2017. Baumgardner faced Nydia Feliciano for the vacant
WBC super featherweight title on February 10, 2018. She captured her first professional championship by unanimous decision. Baumgardner suffered her first loss as a professional in her first WBC International title defense, at the hands of
Christina Linardatou on July 28, 2018. Baumgardner faced Gabriella Mezei on May 10, 2019. She won the fight by a first-round technical knockout, her first stoppage victory in nearly two years. Baumgardner next faced Annette Pabello on November 2, 2019. She won the fight by unanimous decision. Baumgardner was then booked to face Cristina Del Valle Pacheco on December 14, 2019. She won the fight by another first-round technical knockout.
Unified super featherweight champion Baumgardner vs. Harper In October 2021, it was announced that Baumgardner would face
WBC and
IBO female super featherweight champion
Terri Harper on 13 November 2021,
Utilita Arena Sheffield. The fight was aired live on
DAZN in the US and across the world as part of the undercard for Kiko Martinez vs. Kid Galahad. Baumgardner defeated Harper via a fourth round technical knockout. During the fight she dominated the second round and then caught Harper with a vicious right hand in the fourth, resulting in her going unbalanced with her whole body stiffened, which caused the referee to jump in to stop the bout. In December 2021, she signed a multi-fight promotional deal with
Eddie Hearn's
Matchroom Boxing. On 14 December 2021, her fourth round knockout against
Terri Harper was adjudged as the 2021 Female Knockout of the Year by the
World Boxing Council (WBC) as part of the WBC Best of the Year. In January 2021, it was also adjudged as Female Knockout of the Year by BoxingScene.com beating three others including
Zulina Muñoz and
Daniela Romina Bermúdez.
Baumgardner vs. Matthysse In April 2022, Matchroom Boxing announced Baumgardner's first fight under the promotion to take place on 16 April against former
unified featherweight world champion
Edith Soledad Matthysse at the
Manchester Arena. The bout was her first title defense. The fight was televised live on
DAZN as part of the undercard of
Conor Benn's WBA continental title defense bout against
Chris van Heerden.
Baumgardner vs. Mayer In October 2022, Baumgardner cut and outpointed Mikaela Mayer to take the WBC, IBF and WBO titles; scores of two of the cards read 96-95 for Baumgardner, with the third card going to Mayer 97-93. Boxing analysts and former world champions Timothy Bradley and Andre Ward noted Baumgardner's fast start, athletic style, and strong finish that seemingly flustered Mayer. Boxing analyst and boxer Shawn Porter also reported on Baumgardner's noteworthy skillset after the "upset" victory. According to CompuBox stats, Baumgardner outlanded Mayer in total punches 116 to 104, was more efficient in her output landing 35% of punches to Mayer's 29%, and connected with significantly more power shots: Baumgardner landed 82 power shots, nearly doubling Mayer's 43. Choi withdrew from the negotiations on December 13, which led to her being declared a "champion-in-recess" by the sanctioning body, due to her declared injury status. Baumgardner instead faced the next highest ranked WBA contender
Elhem Mekhaled for the now vacant championship. The vacant title bout took place on February 4, 2023, at the
Hulu Theater in
New York City and was broadcast by
DAZN. Baumgardner twice knocked Mekhaled down in the third round, en-route to winning the fight by unanimous decision, with two scorecards of 99–89 and one scorecard of 98–90.
Baumgardner vs. Linardatou II Baumgardner made her first
undisputed world
super featherweight title defense against the former two-time
WBO female
junior-welterweight champion
Christina Linardatou, who handed Baumgardner the sole loss of her professional career, on July 28, 2018, when she was able to beat her by split decision. The championship bout was booked as the main event of a
DAZN broadcast card that took place at The Masonic Temple Detroit in
Detroit, Michigan on July 15, 2023. Baumgardner won the fight by a clear unanimous decision, with two scorecards of 99–91 and one scorecard of 98–92. Matchroom Boxing announced on August 16 that Baumgardner had tested positive for a banned substance on her July 12 sample, but her June 16 and the July 16 samples both came back clean. She denied using any banned substance.
Baumgardner vs. Persoon Baumgardner was scheduled to defend WBC super featherweight title against
Delfine Persoon on September 27, 2024 in Atlanta, GA. The fight was stopped and ruled a No Contest in the fourth round due to a cut Persoon suffered over her right eye from an accidental head clash.
Baumgardner vs. Miranda Baumgardner defended her undisputed super featherweight title against
Jennifer Miranda at
Madison Square Garden in New York on 11 July 2025. She won by unanimous decision.
Signing with Most Valuable Promotions On March 18, 2025, it was announced that Baumgardner had signed with
Most Valuable Promotions.
Baumgardner vs. Beaudoin In September 2025, Baumgardner vacated her WBC title and it was announced she would defend her IBF, WBO and WBA championships against
Leila Beaudoin at the
Kaseya Center in
Miami, Florida on the undercard of the
Jake Paul vs. Gervonta Davis fight on 14 November 2025. However, the event was cancelled less than two weeks before it was set to take place due Davis' legal issues. The contest was rescheduled to take place at the same venue on 19 December 2025 as part of the undercard of the
Jake Paul vs. Anthony Joshua fight. Baumgardner won the bout, which unlike most women's championship fights was contested over 12 three-minute rounds, by unanimous decision.
Baumgardner vs. Shin Baumgardner defended her titles against Bo Mi Re Shin at
The Theater at Madison Square Garden in New York on 17 April 2026, winning via unanimous decision. ==Professional boxing record==