Mikaela Mayer

Mikaela Joslin Mayer (born July 4, 1990) is an American professional boxer who has held world championships in three weight classes. She has held the WBO female welterweight title since September 2024 and was previously unified female super-welterweight and super-featherweight champion. 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.

Amateur career Mayer competed internationally as part of Team USA in the women's 60 kg category at the 2016 Rio Summer Olympics.

Amateur accolades 2016 AIBA Americas Qualifier: Gold Medalist, Lightweight 60 kg (132 lb) 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 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 (96-94) and Michael Alexander (96-95) 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.

In March 2026, it was announced that Mayer signed with Most Valuable Promotions.

Mayer vs. Cameron Holding the unified WBA and WBC female super-welterweight titles, Mayer faced WBO female super-welterweight champion Chantelle Cameron in a championship unification bout at bp pulse LIVE in Birmingham, England, on August 29, 2026. She lost by unanimous decision.

Professional boxing record

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