With a congested field of seven skaters skimming around the Iceberg Skating Palace, Zhou avoided a collision that wiped out three of her rivals then made her dash for gold at the ideal moment.
Approaching the final lap, South Korean teenage sensation Shim Suk-hee was cruising in front when Zhou darted back to the inside and snatched the lead.
Once in front, Zhou never relented, thrusting her arms in the air after surging clear of her rivals to cross the line.
"I was nervous at the beginning, but after I finished it I felt so thrilled," she told reporters.
"I've been through a lot during the past four years. I didn't expect I could come back to the Olympic Games."
Zhou was a teenager when she won the 1,500m in Vancouver and then a gold in the 3,0000m relay. But she was not the favourite this time after Shim established herself as the woman to beat.
Just 17, Shim won at last year's world championship and led for most of Saturday's final before having to settle for silver.
"I'm happy, but not totally happy," she said. "I couldn't run my best race, but it's my first Olympics and I think I did it OK."
Italy's Arianna Fontana finished third to add a bronze medal to the silver she won in Thursday's 500m final.
"My goal was to get into the final and once there to try to do something," Fontana said. "With five laps to go I started to get tired, but I wanted to win that medal."
Fontana had originally finished third in the 500m but was promoted to second after Britain's Elise Christie, who is emerging as one of the unluckiest competitors at the Games, was relegated from second place to eighth for causing a pileup.
Christie again incurred the wrath of officials on Saturday when she was eliminated from the opening round of the 1,500m for failing to cross the finish line.
Although she needed only to finish third in her heat to advance to the quarter-finals, and was coasting along in second place with the finish line in sight, Christie made a last-second decision to try and pass Fontana.
She succeeded but in changing course she veered too far inside and failed to cross the actual finish line, forcing the referee to declare her a non-finisher.
The British team considered an appeal but decided not to protest after watching a replay of the final.
"I've looked at the video and we're talking centimetres here," Christie's coach Nicky Gooch told reporters. "To the letter of the law it's probably right, but she's clearly qualified through that race."
There were more wipeouts in the final when China's Li Jianrou, who won the 500m gold medal, was sent sprawling along with South Korea's Kim Alang and American Emily Scott.
All three slid into the protected boards and out of contention, leaving four skaters in with a chance of a medal.
Of the survivors, the odd one out proved to be Jorien ter Mors of the Netherlands, one of the rare competitors who races in both short- and long-track speed skating.
- Sports & Recreation
- Ice Skating
- Arianna Fontana
- Iceberg Skating Palace