The pay-per-view event will take place at TD Garden, in the UFC's first trip to Boston since October 2019. In addition to the main event, strawweight champion Zhang Weili (23-3) will defend her title against Amanda Lemos (13-2-1) in the co-main event.
It's a quick turnaround for Sterling, 33, who just defended his 135-pound title for the third time against Henry Cejudo on May 6 in Newark, New Jersey. Sterling (23-3) has looked exceptional in his past two outings, submitting former champion TJ Dillashaw in October before scoring a split decision against Cejudo last month.
Originally from New York, Sterling has teased a potential move up to 145 pounds to challenge featherweight champion Alexander Volkanovski.
O'Malley (16-1) is a longtime fan favorite who broke through the rankings in 2022. The 28-year-old fought to an unfortunate no-contest against Pedro Munhoz in July thanks to an accidental eye poke, before upsetting former champion Petr Yan via split decision at UFC 280 in October in Abu Dhabi.
O'Malley is known as one of the hardest hitters in the bantamweight division, with five of his eight wins coming via knockout.