A veteran of 38 professional bouts in the sport, Holm switched to UFC in 2013 and put together a 10-0 record to earn a shot at bantamweight champion Rousey at UFC 193.
Rousey herself was undefeated at 12-0 using her specialist armbar finisher but spent the first round taking head shots as she attempted to put Holm in the manoeuvre.
Then, early in the next session, 34 year-old Holm produced a sweeping left leg swinger that caught Rousey on the side of the head and knocked her unconscious.
As standard UFC rules, Holm was then allowed to smash a couple more punches into the prone Rousey’s head until the referee then dragged her off to cheers from the crowd.
Holm looked disbelieving at what she had just achieved as Rousey had recently become a crossover celebrity and had mad a move into Hollywood movies.
A recent cover shoot for Ring Magazine featuring Rousey was criticised by pound for pound king Floyd Mayweather Jr, although Holm may now be awarded the same honour as she actually has a connection to boxing.
Rematch talk has already begun across the UFC world, although Rousey was unable to speak about a return clause at the post-fight presser after being taken to hospital with a bad concussion.