Om's stunning 168 kilogram clean and jerk gave him an unassailable early lead in the 56 kilogram weight class event after he made the unusual decision to participate in the morning's Group B session, which is usually filled with athletes not expected to challenge for medals.
Om said this was a tactic designed to make the lifters in the evening session nervous.
"I think my plan worked 100 per cent," Om told reporters, breaking into a wide smile.
The North Korean looked on from the stands, more than eight hours after he finished competing, as China's Wu attempted a final lift of 161 kg that would have given him gold, but failed to lock his arms while holding the bar above his head.
That left Wu 4 kg short of Om's combined 293 kg total across the two styles of Olympic lift - the one-phase snatch and the two-stage clean and jerk.
Wu managed to hide his disappointment when he spoke to reporters after leaving the arena, but briefly broke into tears while seated alongside Om in a news conference when a reporter listed his previous achievements.
After regaining his composure Wu said "I am prepared that there might be a dark horse coming out, but I didn't expect it would be from Group B."
Eighteen-year old Valentin Hristov of Azerbaijan won the bronze with a performance inspired by knowing his country's president, Ilham Aliyev, was watching from the stands.
"When he's in the audience it gives me more adrenaline and it gives me more strength," he said.
For China, the failure to secure a second weightlifting gold of the Games added to the earlier disappointment of 17-year-old medal prospect Zhou Jun's chaotic exit from the Women's 53 kg event, where she fail to complete a single lift.
Nevertheless, the strong Chinese contingent in the 6000-seat ExCel arena cheered loudly for Wu as he took to the podium.
"The first placed athlete was amazing, but our guy Wu Jingbiao is amazing too. We're still proud of him," Xin Xiaoqi, a 25 year old Chinese student studying in London, said as she left the stadium.
China were dominant in the weightlifting event in the Beijing Olympics, winning 8 gold medals, but failed to build on the perfect start of female lifter Wang Mingjuan who won 48 kg gold on Saturday.
1. Yun Chol Om (North Korea) 293
2. Jingbiao Wu (China) 289
3. Valentin Hristov (Azerbaijan) 286
4. Le Quoc Toan Tran (Vietnam) 284
5. Jadi Setiadi (Indonesia) 277
6. Jose Lino Montes Gongora (Mexico) 269
7. Sergio Armando Rada Rodriguez (Colombia) 269
8. Carlos Berna (Colombia) 268
9. Florin Ionut Croitoru (Romania) 268
10. Chol Bom Sin (DPR Korea) 258
11. Yasmani Romero (Cuba) 258
12. Tom R Goegebuer (Belgium) 247
13. Manueli Tulo (Fiji) 233
14. Mirco Scarantino (Italy) 225
Sergio Alvarez Boulet (Cuba) DNF
Bekzat Osmonaliev (Kyrgyzstan) DNF
Ruslan Makarov (Uzbekistan) DNF
Khalil El Maoui (Tunisia) DNF