Eighteen-month-old Conor Jr put the fans into a frenzy when he walked onto the mat to show off some of his own moves.
McGregor Sr was addressing his Irish fans before his fight against Khabib Nurmagomedov on Saturday when he received a little surprise.
McGregor Jr came strutting out while his father was telling the fans that he was going to “knock out” his Russian adversary.
The Irish fighter said: “On Saturday night you’re in for a show, trust me on that.
“I’m going to take his head off.”
Mr McGregor’s official photographer became the child’s de facto babysitter after he picked him up and took him off of the stage.
Soon after the toddler left, social media became abuzz with people raving about the young showstopper.
People were tweeting photographs and videos of the surprise visit.
One person tweeted: “He’s already got the million dollar walk.”
Another said: “Now I’m a fan of Conor, and his son.”
Some people decided to poke fun and jokingly critique Conor Jr’s fighting skills.
One Twitter user said: “Look at him. High centre of gravity, undeveloped muscles and very unsteady on his feet.”
Conor Sr also showed pride in his son by later posting various images from the night on Instagram with Jr right in the middle of the posts.
The little McGregor was born on May 5, 2017.
His grandfather Tony McGregor announced he will be getting a sibling by early January 2019.