Aldrich was born to a homeless single mother in Denver, Colorado. She grew up in homeless shelters with her mother and older sister, her father had gone to prison before she was born. Years later, Aldrich's mother established a childcare business which allowed the family to move out of the shelter. When JJ was nine, her mother brought the sisters to taekwondo classes at a local recreation center and by the age of thirteen JJ had already earned her black belt. Around those times, Aldrich's taekwondo teachers introduced her to the mixed martial arts gym – 303 Training Center – where she has been training to this day. Aldrich is of Irish Ancestry.
In 2010 Aldrich began looking for amateur bouts, eventually capturing several amateur titles in various organizations. During her amateur career she faced future UFC athletes like Raquel Pennington, Kailin Curran and Rachael Ostovich.
Invicta
JJ Aldrich made her professional MMA career on September 6, 2014, at and she won the fight via unanimous decision. Her next fight come one year later on February 27, 2015 at, against Jamie Moyle where she lost in round one via rear-naked choke. Aldrich was scheduled to face Daniela Kortmann on September 12, 2015 at ; however Kortmann was forced to pull from the card due to visa issue and was replaced by Rosa Acevedo.She won the fight via first round knockout.
The Ultimate Fighter
JJ Aldrich was a contestant on. In the competition, Aldrich defeated Kristi Lopez by unanimous decision in the elimination round, then lost in the quarterfinals to Tatiana Suarez in round 2 by submission via rear-naked choke.
Freestyle Cage Fighting
Aldrich faced Kathina Caton on September 2016 at Freestyle Cage Fighting 53. She won the fight in round one via technical knockout.
Return to Invicta
Aldrich faced Lynn Alvarez on November 18, 2016 at and she defeated Alvarez via unanimous decision.
Ultimate Fighting Championship
She signed with the UFC to fight Juliana Lima for in Albany, New York on December 9, 2016. Aldrich was a late replacement for Lima's original opponent, Tatiana Suarez, who had to pull out of the bout due to injury. She lost the fight via unanimous decision. Aldrich faced South Korean fighter Chan-Mi Jeon in Jeon's UFC debut for in Auckland, New Zealand on June 11, 2017. She won the fight via unanimous decision. Aldrich faced Danielle Taylor on January 14, 2018 at. She won the fight via unanimous decision. Aldrich faced Polyana Viana on August 4, 2018 at UFC 227. She won the fight via unanimous decision. Aldrich returned to flyweight to face Maycee Barber at on March 23, 2019. Aldrich lost the fight via technical knockout in round two. Aldrich faced Lauren Mueller on October 12, 2019 at UFC on ESPN+ 19 She won the fight via unanimous decision. Aldrich faced Sabina Mazo on January 18, 2020 at UFC 246. She lost the fight by split decision.
Championships and accomplishments
Mixed martial arts
Amateur championships
2014 – Conflict MMA flyweight champion
2013 – Sparta Combat League Amateur flyweight champion
