Rousey chased Holm around the ring at UFC 193 on Sunday — looking for the right hold and taking head shots along the way — until Holm saw an opening 59 seconds into the second round and snapped a kick to the head that immediately dropped her more fancied opponent to the canvas.
Holm (10-0) jumped on the prone Rousey, delivering several blows to her head before the referee intervened, ending Rousey's 12-fight unbeaten run and handing Holm the bantamweight title.
As an ecstatic Holm jumped around the ring, Rousey stayed on the canvas as she received medical treatment amid the roar of a stunned, record UFC crowd.
“She's won a lot of fights and imposed her will on a lot of fighters,” Holm said. “So expect her to be aggressive and impose her will on me.
“She had me on the cage for a minute and obviously she was trying for a take down right there … she had a lot of things she was trying so I'm just glad I put in the practice,” she added.
Rousey, a former judo Olympian, was unbeaten through 12 UFC fights before meeting Holm, and a win would have been her seventh title defense. Instead, Holm, a 34-year-old veteran female boxer from Albuquerque, New Mexico, has the championship belt.
“We figured her aggression was coming, if it didn't that's OK, but with footwork and my career we figured she wouldn't give me that space,” Holm said. “There's been a lot of blood, sweat and tears but it was all worth it.”
Rousey left the stadium to receive treatment for facial cuts at a nearby hospital after the loss and skipped the post-fight media conference.
UFC chief Dana White said a rematch between Holm and Rousey made “a lot of sense” and would put other potential matchups on the backburner.
“Obviously we don't make fights the night of the fight, but the rematch makes a lot of sense,” he said. “The rematch is what the people want to see.”
In the other title bout, a bloodied Joanna Jedrzejczyk outlasted Valerie Letourneau to successfully defend her straw-weight belt in a five-round slugfest.
Jedrzejczyk (11-0) won a unanimous decision over Letourneau (8-4) who offered the champion one of her tougher fights in some time.
Jedrzejczyk, a six-time Muay Thai world champion, built the pressure from the second round with some trademark, lightning-quick combinations to Letourneau's head, while forcing the challenger to keep her distance with some effective kicks.
Organizers announced a crowd of 56,214 at Melbourne's Etihad Stadium, which normally hosts Australian rules football matches. The mark eclipsed the 55,724 fans who attended UFC 129 at Toronto's Rogers Centre in 2011.
Rousey, 28, has taken UFC by storm since her debut in 2012 and her success has led to several movie projects as well the publishing of her autobiography.
But it was Holm's calm confidence and the manner of her win that attracted all the attention Sunday.
“Tonight was one of those moments,” White said. “These are the moments in fighting that make it so crazy and so fun. Tonight was one of those moments.”
Holm, a former undisputed welterweight boxing champion, said the moment of her UFC title victory was “one of those moments that you live for.”
“They're the scariest moments. This fight was a lot for me mentally,” she added. “I couldn't tell you tell you how many times I cried in the gym leading up to this fight.
“It's a lot to take in, but those kinds of fights are the ones where a loss is devastating but a win is that sweet of a victory.”
White said that while most onlookers were shocked by Rousey's loss, he was not one of them.
“At the end of the day I made this fight. I said this was a good fight,” he said. “Holly was the right fight. Ronda had never faced anybody who uses the range and distance the way she does.
“This woman has four times more fights than Ronda does. She's been a world champion,” he said.
In other fights on the undercard, Mark Hunt of New Zealand (11-10-1) won his rematch with Brazil's Antonio Silva (19-8) by technical knockout after the referee stopped the feature heavyweight bout in the first round.
New Zealand-born Australian middleweight Robert Whittaker (16-4) earned a gutsy win on points over Uriah Hall (13-6), while Jared Rosholt (14-2) won a unanimous decision of towering Dutchman Stefan Struve (30-8) in a scrappy opening heavyweight bout of the main card.