Floyd Mayweather, 38, failed to pay the WBO a $200,000 fee to administer the fight by the July 3 deadline.
He had been expected to relinquish the title by now, saying he planned to do so following his points victory over Manny Pacquiao.
Fellow American Timothy Bradley will now become the full belt holder.
After Floyd Mayweather defeated Manny Pacquiao, he had declared he would vacate all his titles in order to give younger fighters the chance to win belts.
A statement on wboboxing.com said: “The WBO World Championship Committee is allowed no other alternative but to cease to recognize Mr. Floyd Mayweather Jr, as the WBO welterweight champion of the world and vacate his title.”
Floyd Mayweather, who still holds the WBA and WBC belts at welterweight, has until July 20 to appeal against the decision.
He is expected to stage one more fight in Las Vegas on September 12, although he has yet to name the opponent.
The WBO created a vacant interim welterweight belt for the June 27 fight between Timothy Bradley and Jessie Vargas.
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