In the opening round, Modafferi faced Shana Dobson and won by TKO due to punches in the first round, allowing her to move on to the next stage of the competition. In the quarterfinals, Modafferi faced Emily Whitmire and won the fight via technical knockout in round one. In the semifinals, Modafferi faced Sijara Eubanks and she lost via unanimous decision after three rounds. UFC return Modafferi was scheduled to face fellow semifinalist Barb Honchak on December 1, 2017 at The Ultimate Fighter 26 Finale. However, on the day of the weigh in, Sijara Eubanks was pulled from the fight for kidney failure and was replaced by Modafferi to face Nicco Montaño for the Flyweight title. She lost the fight via unanimous decision. The fight earned her the Fight of the Night bonus. The rematch between Modafferi and Barb Honchak was rescheduled to take place July 6, 2018 at The Ultimate Fighter 27 Finale. Modafferi won the fight via technical knockout in round two. Modafferi faced Sijara Eubanks at UFC 230 on November 3, 2018. At the weigh-ins, Eubanks weight at 127.2 pounds, 1.2 pounds over the flyweight non-title fight limit of 126 and she was fined 20 percent of her purse, which went to her opponent Modafferi. She lost the fight via unanimous decision. Modafferi faced Antonina Shevchenko on April 20, 2019 at UFC on ESPN+ 7. She won the fight via split decision. The victory earned Modafferi the distinction of being the first female UFC fighter to win a bout in Russia. Modafferi was expected to face Liz Carmouche on July 20, 2019 at UFC on ESPN 4. However, Carmouche was pulled from that bout in favor of a rematch with current champion Valentina Shevchenko in August at UFC Fight Night 156. Modaffer then faced Jennifer Maia in a rematch of their 2016 Invicta FC Flyweight Championship bout, which Maia won via split decision. At the weigh-ins, Maia weighed in at 129 pounds, 3 pounds over the women's flyweight non-title fight limit of 126. As a result she was fined 30 percent of her purse, and the bout proceeded as scheduled at a catchweight. Modafferi lost the fight via unanimous decision. Modafferi faced Maycee Barber on January 18, 2020 at UFC 246. Modafferi won the one-sided fight by unanimous decision. Modafferi faced Lauren Murphy on June 20, 2020 at UFC Fight Night: Blaydes vs. Volkov. She lost the