The woman died Dec. 21, two weeks after falling ill, the official Xinhua News Agency said, citing the Health Ministry. It said lab tests confirmed her infection according to World Health Organization standards.
China's mainland has suffered a total of seven human cases of bird flu. The country also had a suspected case in a 12-year-old girl who died.
The country has reported 26 outbreaks in poultry throughout China since Oct. 19.
It was not clear how the woman, a factory worker in Sanming, a city in coastal Fujian province, contracted the virus.
Doctors found no bird flu symptoms among people who had close contact with her, and no outbreaks have been detected in animals in the area, Xinhua said.
Authorities have destroyed millions of birds to contain outbreaks and are in the midst of a campaign to inoculate all of China's 5.2 billion poultry.
Health officials have warned that China could face new infections in winter and spring, especially during the Lunar New Year holiday in January, when large shipments of poultry are moved around the country to supply family banquets.
The H5N1 virus has killed at least 73 people in Asia since it first appeared more than two years ago, according to the WHO, whose figures were last updated Dec. 23. Almost all the victims were in close contact with birds.
Experts fear the virus could mutate into a new strain that could spread easily from human to human, causing a global pandemic.