Mundine never looked like beating the referee's count.
"We worked on a lot of things but that left hook while going to my right was the plan all along," Horn said.
Manny Pacquiao's conqueror hoped the decisive win positioned him to pursue another world title. "They'll know I'm more dangerous at this weight," Horn said.
Mundine gave credit to his opponent as he farewelled a 25-year sporting career. "Jeff proved tonight he was the better man, got me with a better shot," Mundine said. "I was ready. I prepared myself. It's boxing, you just get caught sometimes."
Mundine had talked a good game in the lead-up to the fight and defended his verbal warfare.
"All the smack talk, all the s*** I talk, you got to build the fight," he said. "We're in the entertainment business."
Mundine's only victory of the night was so short-lived he barely got to savour it.
The Man took more swings at Jeff Horn in the lead up to their fight than he did once he got in the ring on Friday night as he was knocked down less than two minutes into the opening round.
But if there is a silver lining — and it's a big if — to what will likely be his final fight, at least one of his biggest wishes was granted.
All throughout the build-up to the fight Mundine said there was no way he was going to stand for the "white supremacist" Australian national anthem because of the injustice it represented towards indigenous Australians.
He slammed Horn for wanting to fight in front of the Australian flag and for wanting the anthem played. He accused the Queenslander of not even knowing the meaning behind the words as he regularly shamed him for being the beneficiary of "white privilege" — a claim Horn strongly rejected.
Fortunately for Mundine, in his career swan song, he walked out on his own terms — even if he couldn't say the same walking out of the ring. As he waited at the front of his tunnel alongside rugby league star James Roberts, music playing tribute to his indigenous heritage rang out around the stadium.
He smiled as his entourage did the same. Mundine said if any music was to be played, it should be Treat by indigenous artist Yothu Yindi — and that's exactly want blared over the Suncorp Stadium PA as he finally stepped out into the open.
Even as boos threatened to drown out the very song he'd campaigned to have played, Mundine played up to the crowd, turning around and raising his arms.
On a night where the Brisbane crowd revelled in Mundine's failure, he had one last reason to crow.
The anthem was scrapped because of time constraints after the fight started nearly an hour late, meaning Mundine wouldn't have to be forced into a pre-fight protest like he was when he fought Danny Green early last year.
In the end Australia got its wish by seeing Mundine knocked out, but not before he landed one last punch.