Conor McGregor has been fined $150,000 (£121,000) and handed 50 hours of community service after confronting Nate Diaz in a press conference.
The pair launched bottles at each other ahead of August's Ultimate Fighting Championship rematch, leading to a full investigation by the Nevada Athletic Commission.
McGregor, who went on to win the UFC 202 bout on points, has now been punished for his part in the row, while Diaz's case will be heard at a later date.
Commenting on the incident, the 28-year-old wrote on Twitter: "I get fined more than these bums get paid."
McGregor appeared to retire from the sport last April after growing upset with the amount of promotional work he was asked to carry out, only to quickly overturn his decision.