After Charlie Ward picked up a knockout win, "The Notorious" jumped the cage to celebrate with his friend, but then all hell broke loose. The UFC's biggest star was in attendance and stormed the cage before putting hands on referee Marc Goddard.
Goddard and McGregor had to be held apart by the fighters and members of the backroom team, we know this is what he's all about but these ugly scenes could have surely been avoided.
What started as a middle-of-the-road Bellator fight card that was to air on Spike TV on a tape delay due to the time difference between the United States and Ireland took an interesting turn on Friday.
McGregor was grappled by security but ultimately left the cage on his own, returning once more to yell "that was a f-king stoppage" before being ejected from the match by Goddard.
McGregor (21-3) hasn't fought in mixed martial arts in 2017.
McGregor was knocked out by Floyd Mayweather during his pro boxing debut in August. The UFC is now in negotiations regarding McGregor's potential return to the UFC in December, according to recent comments by president Dana White.
It is not immediately clear whether McGregor will face any disciplinary action by the UFC or a regulatory body.