Mikaela Mayer


Mikaela Joslin Mayer is an American professional boxer who has been unified world female super-welterweight champion since October 2025, holding the WBA, WBC and WBO titles. She has also held the WBO welterweight title since September 2024. Mayer is a former unified female super-featherweight world champion, having held the WBO and.IBF titles simultaneously. She has also held the interim WBC female lightweight title. As an amateur, she won a bronze medal at the 2012 World Championships and competed for the U.S. at the 2016 Olympics.
In 2025, Mayer was named Sports Illustrated's Female Fighter of the Year.
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Amateur career

Mayer competed internationally as part of Team USA in the women's 60 kg category at the 2016 Rio Summer Olympics. She defeated Jennifer Chieng in the Round of 16 before being eliminated in the quarterfinal by Russian Anastasia Belyakova, who took a majority decision.

Amateur accolades

Professional career

After signing a promotional deal with Top Rank, Mayer made her professional debut on 5 August 2017, defeating Widnelly Figueroa by first-round knockout.
Mayer beat Ewa Brodnicka by unanimous decision to win the WBO female super-featherweight World title at the MGM Grand in Las Vegas on 31 October 2020. Her Polish opponent had been reigning champion but was stripped of the belt after failing to make the 130-pound weight limit.
On 5 November 2021, she took on IBF female super-featherweight World champion Maïva Hamadouche in a contest that saw both women's titles and the inaugural Ring (magazine)|Ring] female super-featherweight belt on the line. Mayer prevailed by unanimous decision.
Seeking to further unify the division, Mayer faced WBC and IBO champion Alycia Baumgardner in London, England, on 15 October 2022. She lost via split decision with judges John Latham and Steve Gray making Baumgardner the winner, both scoring the fight 96-95, while Terry O’Connor gave it to Mayer 97-93.
Mayer switched to lightweight for her next outing where she was scheduled to face Christina Linardatou on 15 April 2023, but the Greek boxer failed her pre-fight medical. Sweden's Lucy Wildheart stepped in as a last-minute replacement with Mayer winning by unanimous decision to became the interim WBC female lightweight World champion.

Mayer vs. Jonas

Another change in weight division saw Mayer challenge IBF female welterweight World champion Natasha Jonas in Liverpool, England, on 20 January 2024. After a closely fought contest, it was the English boxer who came out on top winning by split decision with judge Diana Drews Milano scoring the fight for Mayer 97-93 but Frank Lombardi and Michael Alexander giving it to Jonas.

WBO Welterweight Champion

Mayer vs. Ryan

Mayer was scheduled to challenge WBO welterweight champion Sandy Ryan in New York on September 27, 2024. She won the fight by majority decision. On the day of the fight, while leaving to the event, Ryan was hit by a tin of paint at her hotel. Two days after the fight Ryan demanded an immediate rematch in light of the paint incident and alleged threats against her and her support team.

Mayer vs. Ryan 2

Mayer made the first defense of her WBO welterweight title in a rematch against Sandy Ryan at Fontainebleau in Las Vegas on 29 March 2025. She won by unanimous decision.

Unified Super-welterweight Championship

Mayer vs. Spencer

Mayer challenged WBA female super-welterweight champion Mary Spencer on October 30, 2025, at Casino de Montreal in Montreal, Canada. The vacant WBC and WBO female super-welterweight titles were also on the line. Mayer won by unanimous decision.

Professional boxing record

No.ResultRecordOpponentTypeRound, timeDateLocationNotes
24Win22–2Mary SpencerUD10Oct 30, 2025Montreal Casino, Montreal, CanadaWon WBA, vacant WBC, and WBO light middleweight titles
23Win21–2Sandy RyanUD10Mar 29, 2025Fontainebleau, Las Vegas, Nevada, U.S.Retained WBO female welterweight title
22Win20–2Sandy RyanMD10Sep 27, 2024The Theater at Madison Square Garden, New York City, New York, U.S.Won WBO female welterweight title
21Loss19–2Natasha JonasSD10Jan 20, 2024Liverpool Arena, Liverpool, EnglandFor IBF female welterweight title
20Win19–1Silvia BortotUD10Sep 2, 2023Manchester Arena, Manchester, England
19Win18–1Lucy WildheartUD10Apr 15, 2023Copper Box Arena, London, EnglandWon vacant WBC interim lightweight title
18Loss17–1Alycia BaumgardnerSD10Oct 15, 2022The O2 Arena, London, EnglandLost WBO, IBF, and The Ring female super featherweight titles;
For WBC female super featherweight title
17Win17–0Jennifer HanUD10Apr 9, 2022OC Fair & Event Center, Costa Mesa, California, U.S.Retained WBO, IBF, The Ring female super featherweight titles
16Win16–0Maïva HamadoucheUD10Nov 5, 2021Virgin Hotels Las Vegas, Paradise, Nevada, U.S.Retained WBO female super featherweight title;
Won IBF and inaugural The Ring super featherweight titles
15Win15–0Érica FaríasUD10Jun 19, 2021Virgin Hotels Las Vegas, Paradise, Nevada, U.S.Retained WBO female super featherweight title
14Win14–0Ewa BrodnickaUD10Oct 31, 2020MGM Grand Conference Center, Paradise, Nevada, U.S.Won vacant WBO female super featherweight title
13Win13–0Helen JosephUD10Jul 14, 2020MGM Grand Conference Center, Paradise, Nevada, U.S.
12Win12–0Alejandra Soledad ZamoraRTD6, 2:00Oct 26, 2019Reno-Sparks Convention Center, Reno, Nevada, U.S.Retained WBC-NABF female super featherweight title
11Win11–0Lizbeth CrespoUD10Jun 15, 2019MGM Grand Garden Arena, Paradise, Nevada, U.S.
10Win10–0Yareli LariosUD8Feb 15, 2019Grand Casino, Hinckley, Minnesota, U.S.Retained WBC-NABF female super featherweight title
9Win9–0Calista SilgadoUD8Dec 14, 2018American Bank Center, Corpus Christi, Texas, U.S.Retained WBC-NABF female super featherweight title
8Win8–0Vanessa BradfordUD8Oct 13, 2018CHI Health Center, Omaha, Nebraska, U.S.Won vacant WBC-NABF female super featherweight title
7Win7–0Edina KissTKO3, 2:00Aug 25, 2018Gila River Arena, Glendale, Arizona, U.S.
6Win6–0Sheena FlamandUD6Jun 30, 2018Chesapeake Energy Arena, Oklahoma City, Oklahoma, U.S.
5Win5–0Baby NansenUD6May 12, 2018Madison Square Garden, New York City, New York, U.S.
4Win4–0Maria SemertzoglouKO1, 0:35Mar 10, 2018StubHub Center, Carson, California, U.S.
3Win3–0Nydia FelicianoMD4Dec 9, 2017The Theater at Madison Square Garden, New York City, New York, U.S.
2Win2–0Allison MartinezTKO3, 0:39Sep 22, 2017Convention Center, Tucson, Arizona, U.S.
1Win1–0Widnelly FigueroaKO1, 1:15Aug 5, 2017Microsoft Theater, Los Angeles, California, U.S.

Personal life

Between 2003 and 2005, Mayer played bass in heavy metal band Lia-Fail, which also included Nita Strauss.