Ostovich began her amateur MMA career in 2010. Over the next three years she amassed an undefeated amateur MMA record of 6-0. Ostovich made her professional MMA debut in January 2014 in her native Hawaii. She went 1-1 before joining Invicta Fighting Championships
Ostovich debuted for the all-female Invicta Fighting Championships in December 2014. She faced Evva Johnson at and won the fight by split decision. In her second bout for the promotion, Ostovich faced Andrea Lee on September 12, 2015, at. She lost the bout via verbal submission to an armbar in the third round. In her third bout for the promotion, Ostovich faced Ariel Beck on May 7, 2016, at. She won the bout via split decision. In her fourth fight for the promotion, Ostovich faced Christine Ferea on January 14, 2017, at. She lost the fight via TKO in the third round, bringing her Invicta FC record to 2-2 before joining The Ultimate Fighter.
The Ultimate Fighter
In August 2017, it was announced that Ostovich would be one of the fighters featured on The Ultimate Fighter 26, where the process to crown the UFC's inaugural 125-pound women's champion will take place. In the opening round, Ostovich defeated Melinda Fábián by rear-naked choke submission. In the quarterfinals, she faced Barb Honchak and lost the bout via unanimous decision.
Ultimate Fighting Championship
Ostovich faced Karine Gevorgyan on December 1, 2017, at. She won the fight via armbar submission in the first round. Ostovich faced Montana De La Rosa on July 6, 2018, at. She lost the fight via rear-naked choke in round three. in 2019. Her arm is in a sling from the armbar. Ostovich was scheduled to face Paige VanZant on January 19, 2019, at UFC on ESPN+ 1. It was reported on November 18, 2018, that Ostovich was violently assaulted, sustaining a broken orbital bone and other injuries, and due to the injuries she sustained, she pulled out from the fight against VanZant. On November 27, the bout between Ostovich and VanZant was confirmed to push through on January 19, 2019, after Ostovich was cleared to fight by her doctor. Ostovich lost the fight by submission via armbar in the second round. Ostovich was scheduled to face Veronica Macedo on August 10, 2019 at UFC on ESPN+ 14, but Ostovich was replaced by Polyana Viana for unknown reasons. Ostovich was scheduled to face Shana Dobson at UFC Fight Night 168 in Auckland, New Zealand on February 23, 2020 at UFC Fight Night 168. However, Ostovich was removed from the bout due to testing positive for ostarine, and she was replaced by Priscila Cachoeira. On June 18, it was announced that Ostovich had accepted a USADA suspension for one year due to testing positive for ostarine, retroactive to January 3, 2020. Ostovich tested positive for Ostarine and GW1516 on January 3, 2020 and she was suspended by USADA for eight months. The prohibited substance were found in her supplement were not listed on the supplement label.
Personal life
Domestic violence
On November 18, 2018, Ostovich was assaulted in her hometown of Honolulu, leaving her with a broken orbital bone. The perpetrator is alleged to be her husband, Arnold Berdon, who is an MMA fighter. Ostovich filed and was granted a temporary restraining order against her husband effective until May 19, 2019. Berdon was arrested on November 20, 2018, for second-degree assault and he was released on a bond of $75,000. The case is under investigation currently by the Honolulu Police Department. A nine-minute video taken by a witness and obtained by Hawaii News Now captures Berdon repeatedly saying "I’m going to murder you. I’m going to fucking murder you," and Ostovich’s cries for help. On December 20, 2018, Berdon plead not guilty in connection with the case. The trial's next hearing was in March 2019, where Berdon pleaded no contest on the case. The sentencing took place on May 16, 2019, in a Honolulu court and Berdon was sentenced to a four year probation in domestic assault. Ostovich's divorce decree was filed with full custody of their six year old daughter.
