American Ryan Garcia weighed 3.2lb over the 140lb limit for Saturday’s light-welterweight contest against compatriot Devin Haney in Brooklyn, New York.
The fight at the Barclays Center will go ahead after Garcia’s team agreed to compensate world champion Haney.
But Garcia, 25, will not be eligible to win Haney’s WBC title.
Garcia’s antics have been criticised in the build-up, with several erratic, often unsubstantiated and defamatory, social media posts in recent months.
The Californian launched a foul-mouthed tirade at both 25-year-old Haney and a member of the crowd at Thursday’s news conference.
He also shook hands with Haney after the champion demanded $500,000 in compensation for every pound Garcia weighed the over the limit, despite the challenger’s team instructing him not to agree to the deal.
Haney posted on social media to say Garcia had “honoured the $500k per pound” deal.
Two-weight world champion Haney has won all 31 pro bouts and is widely considered one of boxing’s pound-for-pound stars.
Garcia boasts 24 wins with one defeat – a stoppage loss to Gervonta Davis in April 2023.