Alex Pereira knocked out Jamahal Hill in the first round to retain his light-heavyweight title at the landmark UFC 300 event in Las Vegas.
Brazil's Pereira, 36, dropped American Hill, 32, with a left hook before finishing the fight with repeated ground strikes.
Pereira has now won seven of his eight UFC bouts in a remarkable two and a half years.
"When I step into the octagon I don't see myself as champion," said Pereira.
"I do the same thing in my personal life. I don't let this belt go to my head ever."
Max Holloway delivered the moment of the night at the T-Mobile Arena as he stopped fellow American Justin Gaethje in the final seconds of the pair's lightweight bout for the symbolic BMF title.
Holloway, 32, pointed to the ground with 10 seconds to go, inviting Gaethje to stand and trade punches, before knocking him out with one second remaining as the pair swung wildly.
In the co-main event, Zhang Weili retained her strawweight title by unanimous decision against compatriot Yan Xiaonan in the UFC's first all-Chinese championship bout.
Following the event, the UFC announced Ireland's Conor McGregor would fight for the first time since July 2021 when he takes on American Michael Chandler at UFC 303 in Las Vegas on 29 June.
The landmark 300 event boasted a strong card top to bottom, with 12 current or former champions in action, including two in the first fight of the night in former flyweight champion Deiveson Figueiredo, who beat former title holder Cody Garbrandt by submission in the second round.
The UFC's efforts in producing a star-studded show are synonymous with past centenary events, with WWE star Brock Lesnar fighting at both, while McGregor and Jon Jones were in contention to appear at UFC 200 before their bouts were cancelled.
The headlining bout between Pereira and Hill was finalised following weeks of negotiations between the UFC and various fighters which did not come to fruition, including Leon Edwards, Israel Adesanya and Dricus du Plessis.
But former middleweight champion Pereira was granted the prestigious headlining slot against Hill and he once again made the most of his opportunity in the spotlight.
Pereira beat Jiri Prochazka in November to become only the ninth fighter to win titles in two weight classes in the UFC, and he achieved that feat in record-breaking time - seven fights.
Hill, meanwhile, was fighting for the first time in 14 months after recovering from a ruptured Achilles sustained in July which forced him to vacate the title.
After the pair traded leg kicks in the opening stages, Pereira started to come forward, applying pressure to Hill.
With Hill retreating, Pereira then dropped the challenger with a left hook before delivering repeated blows on the canvas, forcing the referee to halt the contest.
Following his victory, Pereira hinted at a move up to heavyweight and an attempt to become the UFC's first three-division champion.
"I want to keep continuing defending this belt, and I know there needs to be a lot promotion around this fight, but I want a fight at heavyweight," he said.
UFC president Dana White announced in Thursday's press conference that fighters would be awarded $300,000 (£239,000) performance and fight-of-the-night bonuses at the event, up from the standard $50,000 prize.
And Holloway, stepping up to lightweight from featherweight to contest for Gaethje's BMF title, delivered a moment befitting of the prize.
After largely outclassing the 35-year-old over five rounds and heading for a decision win, Holloway risked defeat by inviting Gaethje to stand and trade punches with 10 seconds remaining.
But, with the final bell looming, Holloway cemented victory, connecting with a left hook which sent Gaethje crumbling to the canvas and wowing the sell-out crowd.
Former heavyweight champion Mark Coleman, who was treated in hospital last month after saving his parents from a house fire, then wrapped the commemorative belt around Holloway, awarded to the UFC's 'baddest' fighter.
"Give it up to Gaethje - he's the real BMF. He had so much to lose and nothing to gain from this fight," said Holloway.
Double Olympic judo gold medallist Kayla Harrison was victorious on her UFC debut as she dominated fellow American Holly Holm, forcing the former bantamweight champion to submit in the second round to a rear-naked choke.
Former two-weight champion Amanda Nunes, who retired last year, then teased a potential return and match-up with Harrison by responding to footage of Harrison's post-fight interview on social media., external
