The nomination of Chan, a senior WHO official and former Hong Kong health chief who dealt with bird flu and Severe Acute Respiratory Syndrome (SARS), needs the approval of at least two-thirds of the UN health agency's full assembly of 193 members, in a vote due on Thursday.
That was expected to be a formality in keeping with previous appointments.
"Dr Margaret Chan of China was nominated today by the executive board of the World Health Organisation for the post of director-general," the agency announced in a statement after the board's meeting behind closed doors.
Chan pledged to follow the course set by her predecessors.
"Rest assured that I will work tirelessly with my eyes on the goals we agreed on together, my ears open to the voices of all, and my heart committed to the populations of our countries," she told the board in a public session.
With 24 votes, Chan beat off her closest challenger, Mexico's reformist Health Minister Julio Frenk, who received 10 votes, diplomats at WHO headquarters said.
The three other remaining candidates, including Spanish Health Minister Elena Salgado, were eliminated in earlier voting.
Chan, who was until recently an assistant director general at the agency, championed health for developing countries in her campaign for the top post. Her nomination came just days after her official backer, China, hosted an unprecedented two-day summit with 48 African nations in Beijing.
It also sets the Asian giant on course to gain its most prestigious post ever in the United Nations.
China expressed its "gratitude" to the governing board for the nomination.
Chan paid tribute to the late director general, South Korean Lee Jong Wook, who died suddenly in May, and his partly unsuccessful but continuing initiative to deliver life-saving drugs to three million people struggling with HIVAIDS in poor countries by 2005.
"He will always be remembered for the Three-by-Five Initiative, that was all about preventing untimely deaths on the grandest scale possible," Chan said. "If my nomination is confirmed by the WHO assembly tomorrow, I intend to take the legacy of Dr Lee and his predecessors forward," she added.
Chan gained initial praise as Hong Kong's health chief from 1994. However, she later faced a barrage of criticism of her handling of the SARS crisis.
She first drew international attention with her swift action in ordering the cull of 1.4 million local poultry that halted an intial outbreak of H5N1 bird flu in the then British colony.
The outlook on Hong Kong's preparedness changed in 2003 when SARS, a then unknown deadly pneumonia-like disease, entered the city from China and spread rapidly.
In 2003, she joined the WHO under Lee, where she in swift succession rose from managing environmental health, to head the epidemic alert department and then lead the agency's efforts against communicable disease.

Copyright AFP (Agence France-Presse), 2006