Outside the Haidian office, Yuan Bo and Gao Qiong posed in the snow as a passerby took a snapshot of them with their newly stamped marriage certificate.
"We're so lucky - we even got registered at 12 am. It was a coincidence," said Yuan, 28, an IT worker.
The couple, who had been together since high school in East China's Anhui province, said they were going shopping for jewelry later.
For Zhu Yanyan in Shanghai, the date she chose to wed her fiance could not have had more meaning: Not only had the couple been together for 12 years, but she said her English name is Twelve.
"We also wanted to get married before Dec 21, which, as legend has it, will be the end of the world," the 30-year-old joked.
According to the Shanghai Civil Affairs Bureau, 4,883 couples were registered for marriage on Wednesday, a record for the year.