Mackenzie Dern

Dern began training by the age of three and practicing with her father and stepmother who is also a black belt, Luciana Tavares. Mackenzie started competing at a young age, and began competing in the adult divisions at 14 years old. She has won a world championship in every belt level as she progressed to black belt rank, which was awarded to her by her father in December 2012, three months prior to her 20th birthday. She graduated from Ironwood High School in Glendale, Arizona.

Dern fought under Legacy Fighting Alliance with a record of 4–0 prior to signing with Invicta Fighting Championship (Invicta) in November 2017.

Dern made her Invicta debut on December 8, 2017, at Invicta FC 26: Maia vs. Niedzwiedz against Kaline Medeiros. She won the fight via an armbar in round three.

Dern made her promotional debut against Ashley Yoder on March 3, 2018, at UFC 222. She won the fight via split decision.

Dern faced Amanda Cooper on May 12, 2018 at UFC 224. At the weigh-ins, Dern weighed in at 123 pounds, 7 pounds over the strawweight non-title fight upper limit of 116 pounds. As a result, the bout proceeded at catchweight and Dern was fined 30% of her purse. Dern won the fight via submission through a rear naked choke in the first round.

After a hiatus from maternity leave, Dern faced Amanda Ribas on October 12, 2019 at UFC on ESPN+ 19. She lost the fight via unanimous decision.

In February 2019, Dern announced that she had put her MMA career on hold due to pregnancy. Her daughter, Moa, was born on June 9, 2019.

Dern was expected to face Ariane Carnelossi on April 25, 2020 at UFC Fight Night 173. Carnelossi was forced to withdraw from the bout due to travel restriction.

Dern was scheduled to face Hannah Cifers on April 25, 2020. However, on April 9 the promotion announced that this event was postponed. The pairing eventually took place on May 30, 2020 at UFC on ESPN: Woodley vs. Burns. Dern won the fight with a first round kneebar - becoming the first woman to finish a fight by any form of leg lock in UFC history. This win also earned her her first Performance of the Night award.

Dern faced Randa Markos on September 19, 2020 at UFC Fight Night 178. She won the fight via submission in the first round. This win earned her her second straight Performance of the Night award.