Bantamweight champion Kayla Harrison faced former two-division titleholder Amanda Nunes in the UFC 334 co-main event at Madison Square Garden in New York, in what was widely described as one of the biggest women's fights in the promotion's history. It was Nunes' first fight in three years; she had retired after winning back the crown at UFC 289 in June 2023. Harrison, a two-time Olympic judo gold medalist and the only American to achieve that feat, entered as the favorite at -158 against Nunes at +134 per FanDuel, and was ranked No. 3 in the MMA Fighting Pound-for-Pound Rankings with a 19-1 record.

Harrison captured the title with a submission over Julianna Pena in June 2025, setting up the bout with her former teammate; the two had trained together at American Top Team, and Harrison had been sidelined for 17 months due to neck surgery before returning healthy. Nunes, 23-5, had gone on a 14-1 run from 2015 to 2023 that included titles at bantamweight and featherweight and eight successful title defenses, and she was seeking to become a three-time bantamweight champion.S1S2

The fight was competitive early. In the first round Nunes landed hard right hands and leg kicks while Harrison struggled to close distance, but Harrison secured a takedown, landed a judo throw and controlled Nunes with left hands from side control, and MMAWeekly scored the round 10-9 for Harrison while MMA Fighting scored it 10-9 for Nunes. In the second round Nunes pressed forward and took Harrison down, but Harrison reversed position, landed an elbow that cut Nunes on the forehead and finished with left hands from top position, a round MMAWeekly also scored 10-9 for Harrison.S1S2

Nunes came out pressing in the fourth round, landing right hands, but Harrison caught a kick and took her down, took her back and sank in a rear-naked choke. Nunes tapped out at 1:29 of the fourth round, giving Harrison the submission victory and her second title defense in the bantamweight division.S1