Kashirina, conceding 28kg in bodyweight to her rival, took the initiative as she became the first-ever woman to snatch over 150kg.
But Zhou hit back to equal the world best clean and jerk of 187kg - the only record still standing after a crunch clash - and triumph in dramatic fashion by just a single kilogram overall.
Zhou's total of 333kg breaks her own previous world best by a clear five kilos and adds the Olympic title to the world crown she claimed in Paris last November, where she also pushed four-time European champion Kashirina into second place.
Such was the dominance of the leading duo that a total of 294kg claimed bronze for Armenia's Hripsime Khurshudyan, who edged out 2008 gold medallist Jang Mi-Ran (289kg).
The competition provided a mammoth range of +75kg lifters, with Ghana's Alberta Boatema Ampomah weighing in at 78.53kg and USA's Holley Mangold topping the scales at 157.04kg.
Mangold was supported in the ExCeL crowd by brother and NFL's New York Jets centre Nick, but it was not enough to prevent her from finishing in 10th place overall.
The battle for the medals was always set to be between Zhou and Kashirina.
Amazingly, both started their snatch attempts above the Olympic record of 140kg and, with a new Games best set five times in six lifts, it finished with Kashirina twice eclipsing her own world record of 148kg to end with a stunning third lift of 151kg.
After the remaining 12 competitors had completed their three clean and jerk attempts, the pair were left to battle it out for gold and silver as a host of further records were repeatedly crushed.
And it was an Olympic and equal world best of 187kg which proved decisive as Zhou successfully raised it on her second attempt but Kashirina did not get close on her final lift.
It resulted in Zhou triumphing by a total of 333kg to 332kg, sealing her place as the strongest female in the world as the women's weightlifting at London 2012 was brought to a close.
The title 'world's strongest woman' is one Zhou will cherish, and she insists she does not pay any attention to negative criticism of her 5ft 9in, 20st 9lb frame
"I like weightlifting, so when you like something you don't think whether it's bad for your body shape or it's not feminine," she said.
"You don't think about those things, I just do what I like."
Victory takes China's weightlifting tally to five gold and two silver at London 2012 compared to eight gold and one silver in Beijing four years ago, and Zhou insists her medal goes some way to making these Games a success for her team.
"I can say we feel mission accomplished because men's weightlifting lost two gold medals," she said.
Sunday's thrilling session means the total number of world and Olympic weightlifting records broken over the past nine days is approaching 40, and silver medallist Kashirina puts the success down to two key aspects.
"I think it all stems from training and then from determination, single-minded determination," she said.
"Every athlete dreams of making it to the Olympic Games one day and then once there to become a challenger for medals and then to break world medals. This I think is what the Olympic Games are all about."
Bronze was Armenia's first medal of 2012 and Khurshudyan is expecting a rousing reception when she returns home.
"Everyone is going to be thrilled because this is the first medal for my country at these Games, so everyone is going to be meeting me at home," she added.