She has been called the greatest female strawweight mixed martial artist of all time, including by Daniel Cormier, who credited her with putting the weight class "on the map".

Over the next two years, she continued her undefeated streak with five successful title defenses against opponents such as Jessica Penne, Cláudia Gadelha, and Jéssica Andrade.

Jędrzejczyk lost by split decision in what many pundits called the greatest fight in women's MMA history.

Following a two-year layoff, Jędrzejczyk retired from mixed martial arts in June 2022 after losing a rematch against Zhang at UFC 275.

Jędrzejczyk discovered Muay Thai when she was 16, while taking up fitness, which eventually led her to compete in national and European tournaments.

[13] On June 20, 2013, at Battle of Moscow 12 she defeated the then #1 Russian WMMA flyweight fighter Julia Berezikova via unanimous decision.

[17] She made her promotional debut, now fighting as a strawweight, on July 26, 2014, at UFC on Fox: Lawler vs. Brown against Juliana Lima.

[18] Jędrzejczyk next faced undefeated strawweight top contender Cláudia Gadelha on December 13, 2014, at UFC on Fox 13.

The judges' decision was met with much controversy as the majority of the MMA media scored the bout in favor of Gadelha.

She successfully defended the title against Penne, defeating her in the third round via TKO following a flurry of punches and a knee against the cage.

[28] In early 2016, the UFC announced that Jędrzejczyk would be one of the coaches, opposite former opponent Cláudia Gadelha on The Ultimate Fighter 23.

A rematch between the two took place on July 8, 2016, at The Ultimate Fighter 23 Finale[29] in the MGM Grand Garden Arena in Las Vegas, Nevada.

[31] Jędrzejczyk successfully defended her title for the 4th consecutive time by defeating fellow Pole Karolina Kowalkiewicz by unanimous decision on November 12, 2016, at UFC 205 in Madison Square Garden, the first event the promotion had held in the historic arena.

[34] For her sixth title defense, Jędrzejczyk faced Rose Namajunas at UFC 217 at Madison Square Garden in New York on November 4, 2017.

In a huge upset, she lost the bout via KO (punches) in the first round, marking her first professional loss in mixed martial arts competition.

[63] SportsJoe.ie MMA journalist Darragh Murphy summed up her fighting style: "Her technique has the right combination of sublimity and relentlessness, expressing one's typically violent art through beauty, the perfect storm.

[71][73][74] UFC president Dana White has praised her stating "She is so bad ass... pound-for-pound [she is the] best female fighter on Earth...

These are the key ingredients of successful takedown defense, and the elements that make Joanna Jędrzejczyk and José Aldo such masterful strikers.

"[60] The Washington Post striking analyst Patrick Wyman wrote that "sound fundamentals fuel the best fighters in the world, and nobody has better mastered the bread and butter of footwork and distance management than Aldo and Jedrzejczyk".