After a cagey opening frame that saw Pereira target Adesanya's lead leg with brutal kicks, the fight burst into life in the second, with both men landing head kicks early and Adesanya's crisp boxing beginning to tell.
With the second round winding down, Adesanya was backed up against the cage but he suddenly uncorked a huge right hand and followed it up with another to knock Pereira out cold and take back the belt he lost to the Brazilian in November.
Adesanya followed Pereira down to the mat but referee Dan Mirgliotta waved the fight off, returning the Nigerian-born New Zealander to the top of the middleweight pile, a weight class he has dominated for the last four years.
"I played possum a bit ... look at me, I am here, he is here, that last one (punch) had everything. That last hammer fist was from the gods," Adesanya said in a post-fight interview in the cage.
He told the fans in attendance that he hoped they would have the chance to feel the same joy that he was feeling in that moment.
"If you stay down, you will never ever get that resolve. Fortify your mind and feel this level of happiness as you rise," said Adesanya, who had never beaten Pereira in MMA or kickboxing in three previous meetings.