Paul, 24, was met with chants of 'f**k Jake' by the 15,000-strong crowd at the VyStar Veterans Memorial Arena in Jacksonville, Florida.
The American star's professional boxing career has seen him hold an undefeated record after three fights, with his most recent victory coming over former UFC fighter Ben Askren.
But Paul's presence at UFC 261 led to more than fan backlash as retired MMA fighter Cormier entered into a war of words with him during their standoff.
Cormier revealed on commentary to fellow UFC legend Joe Rogan that he threatened to 'slap the s**t out' of Paul.
The 42-year-old UFC commentator explained: "I swear to God, I just saw Jake Paul.
Daniel Cormier online- Jake Paul (@jakepaul) April 25, 2021
"Imma Smack Jake Paul when I see him"
Daniel Cormier in person... pic.twitter.com/zHnssneYBV
"I pointed at him, I said, 'Don't play with me.' Because I'll slap that s**t out of him. I don't play those games."
Paul previously called out Cormier on social media and branded the UFC legend "fat boy."
Okay fat boy. So me vs you & J vs. T.?? https://t.co/MDhyPTVpIN- Jake Paul (@jakepaul) April 18, 2021
BOUTTA COOK HIM UP CLEVELAND STYLE- Jake Paul (@jakepaul) April 18, 2021
Cormier, who retired after his defeat to Stipe Miocic at UFC 252 last August, previously hit out at Paul by saying that the "dude would never fight me."
The ex-UFC heavyweight champ added that he "would kill him" in a fight, but he ruled out the idea of stepping into the squared circle with him.
Speaking on ESPN's DC & Helwani podcast, Cormier explained: "If he continues to fight guys like this, he will continue to look as he's looked.
"But the moment he fights somebody that has a better understanding of boxing, that combination isn't going to land as effectively, and even if it does, he's not gonna just be putting these dudes out.
"Guys are gonna start rolling with the punch, they're gonna stop reacting so bad to the jab to the body.
"This dude would never fight me. I would kill him. Why would I ever fight someone like that?"
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