Ivanov, 22, won the title at the new weight on his last lift of the competition, but insisted he was giving up weightlifting to spend more time with his wife and son.
The International Weightlifting Federation, which also counts an Olympic gold as a world title, changed the weight divisions at the beginning of the year in an effort to clean up the sport, as many previous world records were believed to be drug-aided.
Ivanov was run close by Turkey's Halil Mutlu, who was leading the lightest division in the 65th men's championships until Ivanov cleared 157.5 kg on his third jerk. Mutlu, 20, equalled the 275kg that he lifted to win the world junior title earlier this year.
Ivanov, who has never won the snatch competition in any of his world title wins, came fourth this time with a 120.0kg lift. The event was won by China's Yang Bin with a lift of 122.5kg.
Organisers were embarrassed that they could not raise the South Korean flag for Kwang-Ku, who took the bronze, during the presentation: it was stolen, along with 20 other flags, after the opening ceremony.Reuse content