In 1979, Minter won all four of his fights, two of them by knockout. On 16 March 1980, in Las Vegas, he was given a shot at World Middleweight Champion Vito Antuofermo's title at the Caesars Palace. He won the title by a 15-round decision and, in a rematch, he retained the world title by a TKO in eight rounds. Minter's run as world champion came to an end on 27 September of that year, when he was stopped on cuts in three rounds to Marvin Hagler at Wembley Arena in London. After the fight was stopped, Minter's supporters caused a riot, throwing beer cans and bottles into the ring and both boxers had to be ushered away by the police.