Yang Yang, putting behind her a dismal fourth place finish in the 1,500m three days ago, led from start to finish to cross the line in 44.187 seconds.
World-record holder and four-time European champion Evgenia Radanova followed home 0.065 seconds behind.
Another Chinese, Wang Chunju, the world champion in the shortest distance came in third, two-hundredths of a second further behind.
Return to form
Yang was happy make up for her disappointing fourth in the 1,500m earlier in the Games.
"It was a nightmare after the 1,500m loss," Yang said.
"I felt too much pressure. I cried several times. I could not sleep."
But she said that a meeting with members of the Chinese Olympic delegation helped calm her down.
"I felt liberated later, and that's how I adjusted myself to compete in this 500m.
Yang's name is tagged with the letter A to distinguish her from her younger team-mate and namesake Yang Yang (S).
The 25-year-old is also the overall World Cup winner this season with the top points in the 1,000m and 1,500m.
Yang Yang (S) did not compete in the 500 metres.