Mikaela Mayer was born on July 4, 1990, in the Los Angeles area of California, the youngest of three daughters raised by her father, Mark Mayer, alongside two older sisters (TheCityCeleb). Long before she laced up boxing gloves, a 12-year-old Mayer answered an ad claiming to be a year older and became the bassist for Lia-Fail, an all-female hardcore band that debuted at the Whisky A Go Go in West Hollywood in September 2003 alongside guitarist Nita Strauss, later of Alice Cooper’s band. The group toured through 2005 before splitting up on the road, and Mayer has since said of walking away from music, “I was just done. Like if I could go back and just tell my 14-year-old self just don’t stop playing” (ESPN). After a directionless stretch as a teenager, she walked into a Muay Thai gym at 17, discovered boxing, and eventually earned a boxing scholarship to Northern Michigan University’s Olympic Education Center, the only boxing scholarship program in the United States at the time since the sport is not NCAA-sanctioned (Wikipedia).

Mayer built one of the more decorated amateur resumes in American women’s boxing, winning a bronze medal at the 2012 AIBA Women’s World Boxing Championships, collecting national titles in 2012, 2014 and 2015, and taking gold at the 2016 AIBA Americas Qualifier to punch her ticket to Rio. At the 2016 Olympics she competed in the women’s 60kg lightweight division, defeating Jennifer Chieng in the round of 16 before losing a majority decision to Russia’s Anastasia Belyakova in the quarterfinal (Wikipedia). She turned professional on August 5, 2017, with a first-round knockout of Widnelly Figueroa, signing with Bob Arum’s Top Rank and inking a sponsorship deal with Everlast that made her the first woman to hold multi-year agreements with both organizations, a distinction that gave her an early financial foundation most female boxers of her generation did not have (TheCityCeleb).

Mayer’s professional breakthrough came at super featherweight, where she outpointed Ewa Brodnicka for the vacant WBO title on October 31, 2020, then unified that belt with the IBF strap by decisioning France’s Maiva Hamadouche on November 5, 2021. She retained the undisputed-leaning titles against Jennifer Han in April 2022 before suffering the first loss of her career on October 15, 2022, dropping a split decision to Alycia Baumgardner in London in a fight widely regarded as one of the best in women’s boxing that year. Mayer moved up in weight afterward, capturing the interim WBC lightweight title with a decision win over Lucy Wildheart in April 2023 as she rebuilt toward bigger opportunities (Wikipedia).

After a January 2024 split-decision loss to Natasha Jonas in an IBF welterweight title challenge in Liverpool, Mayer regrouped and won the WBO welterweight title from Sandy Ryan by majority decision at Madison Square Garden on September 27, 2024, then defended it against Ryan in a unanimous-decision rematch in Las Vegas on March 29, 2025. She capped a career-best year by moving up again to junior middleweight and dominating unified champion Mary Spencer over ten rounds in Montreal on October 30, 2025, capturing the WBA, WBC and WBO titles to become a world champion in a third weight class (Wikipedia). That run pushed her professional record to 22 wins against 2 losses, with 5 by knockout, on top of her 2016 Olympic appearance and 2012 world amateur bronze medal.

Mayer’s 2025 campaign, three world titles across three divisions capped by the win over Mary Spencer, earned her Sports Illustrated’s Female Fighter of the Year award at the magazine’s Sportsperson of the Year Awards ceremony on January 7, 2026, where she appeared alongside fellow boxers Laila Ali and Seniesa Estrada (Yahoo Entertainment). The recognition arrived as she was already established as one of the sport’s most consistently featured female fighters on major cards, and she is scheduled to headline a unification bout against WBO super-welterweight titleholder Chantelle Cameron in Birmingham, England, on August 29, 2026.

Beyond her long-running Everlast partnership, Mayer’s sponsorship portfolio has included deals with DLX Boxing Gym, Victory Boxing Club, JP Athletics and Contenders, income streams that supplement her fight purses between bouts (EssentiallySports). As with most female boxers outside the sport’s very top tier of pay-per-view stars, her endorsement income remains modest relative to her fight-night earnings, though her status as the first woman to sign multi-year deals with both Everlast and Top Rank gave her a level of sponsor stability early in her career that many peers lacked.

Mayer’s clearest business move to date came on March 13, 2026, when she signed a multifight promotional deal with Jake Paul and Nakisa Bidarian’s Most Valuable Promotions, joining what the company describes as the largest women’s boxing roster in the sport, more than 40 fighters including 22 world champions. MVP co-founders Paul and Bidarian called her “one of the most accomplished fighters in women’s boxing and a proven champion across multiple weight classes,” while Mayer said, “I’m thrilled to join Most Valuable Promotions as we continue breaking barriers and elevating women’s boxing to new heights” (Sports Illustrated). Specific financial terms were not disclosed, but the move positions her for greater platform exposure through MVP’s multiyear ESPN broadcast deal for women’s boxing, which could meaningfully raise her future purses beyond what her Top Rank-era fights paid.

There is no reliable public record of Mayer owning real estate, vehicles or other major assets that have been independently reported on. Outlets that track her finances in detail, including Sporty Salaries’ itemized breakdown of her fight-by-fight purses and EssentiallySports’ purse-history reporting, document her boxing income fight by fight but do not report any property or vehicle purchases (Sporty Salaries). That stands in contrast to some of her better-known male contemporaries, whose home and car purchases are frequently documented in sports media, and likely reflects both her comparatively lower purses over most of her career and a public profile that has stayed focused on her in-ring accomplishments rather than lifestyle coverage.