Torokhtiy lifted 185 kilograms in the snatch and 227 kilograms in the clean and jerk for a total of 412 kilograms, just one 1 kilo more than silver medallist Navab Nasirshelal of Iran.
Poland's Bartlomiej Bonk got bronze at 410 kilograms, putting all three medallists within a 2-kilogram range.
Three-time world champion Marcin Dolega, also of Poland, was eliminated after three failed attempts in the snatch.
The results were modest for a weightlifting competition where world or Olympic records have been broken almost every day. Torokhtiy's total was 3 kilograms lower than that of 94-kilogram champion Ilya Ilyin of Kazakhstan.
The Ukrainian benefited from the fact that the top-ranked competitors in the 105-kilogram weight class didn't compete.
The defending champion from the 2008 Olympics, Andrei Aramnau of Belarus, didn't come to London, citing a leg injury.
Beijing silver medallist Dmitry Klokov and 2011 world champion Khadzhimurat Akkaev, both Russians, withdrew at the last moment, citing injuries.
Torokhtiy acknowledged the result might have been different if the Russians had competed. "But I think we will have a chance to compete again and then we'll see who is the strongest," he said.
Akkaev and Russian head coach David Rigert appeared at a news conference later Monday in an apparent attempt to dispel rumours that the late withdrawals were related to doping suspicions.
Akkaev said he had emergency back surgery in London on Aug. 2 on a herniated disk. On Rigert's suggestion, he lifted his shirt, removed a brace and unveiled a bandage on his lower back.
Klokov's situation was less clear. The official competition documents said he couldn't compete because he had injured his back, but Rigert said it was his right knee.
Rigert said that he kept Klokov on the entry list, hoping he would recover in time to fly to London, "but unfortunately the injury was really serious. We waited literally until the last minute."