Jarrell Miller was denied a license to box by the New York State Athletic Commission (NYSAC) over a failed drug test on Wednesday, scuppering his planned June 1 bout with world heavyweight champion Anthony Joshua.
In a statement quoted by US media outlets, the NYSAC said Miller was barred from fighting in the state following the news of his positive doping case.
"The New York State Athletic Commission has denied Jarrell Miller's professional boxing license application for a violation relating to the use of a prohibited substance. We have no further comment at this time," the commission said.
Miller, who is undefeated in his 24 professional fights, was due to take on the Briton at Madison Square Garden for the WBA, IBF and WBO titles on June 1.
However on Tuesday it emerged Miller had tested positive for a banned substance following a test conducted by the Voluntary Anti-Doping Association (VADA) on March 20.
"We have been informed by VADA that there has been an adverse finding in Jarrell Miller's sample collected on March 20th, 2019," Eddie Hearn, Joshua's promoter, tweeted.
Miller previously served a nine-month ban from the California State Athletic Commission after testing positive for methylhexaneamine when kickboxing in 2014.
During their promotional tour for the fight, Miller revealed that both fighters had agreed to between 10 and 12 weeks of drug testing in the build-up to the bout.
ESPN reported that Joshua still planned to make his US debut as planned in June for what will be his seventh title defence.
Promoter Hearn said he was scrambling to find an alternative opponent.
"I am on the search for a new opponent," Hearn said. "Literally anyone can get it. There are some names that would appeal to our partners - DAZN, Sky Sports and Madison Square Garden - more than others and it's our job to get the ones that appeal most. I've spoken to 16 heavyweights in the last 24 hours, 10 of which are not suitable."