Genetic analysis indicated the virus spread directly from poultry to the victim, who died Saturday in the southern city of Shenzhen, the Shenzhen Disease Control Center said in a statement reported by the official Xinhua News Agency.
"Though it is highly pathogenic to human beings, the virus can not spread among people," the statement said, according to Xinhua. "There is no need for Shenzhen citizens to panic."
H5N1 rarely infects humans and usually only those who come into close contact with diseased poultry. Scientists are closely watching the virus for any signs it is becoming more easily transmissible from human to human.
A 39-year-old bus driver surnamed Chen developed a fever Dec. 21 and was hospitalized Dec. 25, according to an earlier statement by city and provincial authorities. The provincial health department said Health Ministry experts confirmed Saturday that he was infected with H5N1.
Xinhua said health authorities still were trying to figure out where he was infected.
The Guangdong health department has said 120 people who had close contact with Chen have not developed any abnormal symptoms.
The World Health Organization says globally 336 people have died from 573 confirmed bird flu cases since 2003. Of these, 40 cases were in China, 26 of which were fatal.
Chen's death was a week after two dead birds tested positive for the virus in Hong Kong, which is just across a river from Shenzhen.
More than 19,000 birds at a Hong Kong market were slaughtered and imports and sales of live poultry were banned for three weeks after a chicken carcass tested positive for H5N1. Lab tests later confirmed that an Oriental magpie robin found dead on Dec. 17 was also infected.
China's last reported human case of H5N1 was in June 2010. A pregnant 22-year-old woman from central Hubei province died after being exposed to sick and dead poultry.