Huang and Zheng Siwei claimed the sport's first gold of the Paris Games when they demolished South Korea's Kim Won-ho and Jeong Na-eun 21-8, 21-11 in just 41 minutes.
The pair received their medals at La Chapelle Arena and then climbed down off the podium for a victory lap.
Waiting in the far corner was Huang's boyfriend Liu Yuchen, a men's doubles player who won silver in Tokyo three years ago and exited in the group stage in Paris.
Liu presented Huang with a bunch of flowers before whipping out a ring and getting down on one knee, much to the delight of the Chinese fans packed into the arena.
Huang said the proposal had been "very surprising".
"I had been preparing for the match," said the 30-year-old, showing off her ring to reporters.
"Today I became an Olympic champion and I got engaged. I think the ring fits my finger really well."
Huang and Zheng stormed into an early lead and took the first game in less than 20 minutes.
The South Korean pair made a better start to the second game but their Chinese opponents were relentless, closing out the match when Jeong hit a return wide.
Zheng and Huang lost in the final in Tokyo three years ago and Zheng said they had learned their lesson.
"In Tokyo we didn't prepare very wisely," he said. "We worked very hard then but this time we have trained and played in a smarter way.
"That's why I felt we could perform better this time."
Japan's Yuta Watanabe and Arisa Higashino took bronze after a 21-13, 22-20 win over South Korea's Seo Seung-jae and Chae Yu-jung.
China have topped the badminton medals table at the past six Olympics.
They are guaranteed another gold when Chen Qingchen and Jia Yifan take on Liu Shengshu and Tan Ning in an all-Chinese women's doubles final on Saturday.
Chinese top seeds Liang Weikeng and Wang Chan reached the men's doubles final, where they will take on Taiwan's defending champions Lee Yang and Wang Chi-lin.
