WASHINGTON — The World Trade Organization on Monday officially selected Ngozi Okonjo-Iweala, a Nigerian economist and former finance minister, to be its next leader. The first woman and first African to serve as director-general, Dr. Okonjo-Iweala will assume the post on March 1 for a renewable term expiring on Aug. 31, 2025.

Dr. Okonjo-Iweala said in a statement that she was honored to have been selected and would work with the organization’s member countries to address health issues brought about by the pandemic and “get the global economy going again.”

“A strong W.T.O. is vital if we are to recover fully and rapidly from the devastation wrought by the Covid-19 pandemic,” Dr. Okonjo-Iweala said. “Our organization faces a great many challenges but working together we can collectively make the W.T.O. stronger, more agile and better adapted to the realities of today.”

Dr. Okonjo-Iweala takes the helm of the W.T.O. at a particularly difficult time for the global trade body, which was created in 1995 to help settle trade disputes, write new trade rules and encourage the flow of goods and services worldwide.

The organization’s many critics say it has fallen short on several of those fronts, including failing to advance new trade negotiations and adequately police unfair economic behavior from China. At a time of growing global protectionism and deep uncertainty for the global economy brought about by the pandemic, the organization’s system for dispute settlement also remains crippled after challenges from the Trump administration.

In an acceptance speech given by video link to a mostly empty meeting room in the W.T.O.’s headquarters on Lake Geneva in Switzerland, Dr. Okonjo-Iweala acknowledged those challenges but struck a hopeful note about how her leadership could help build a stronger, more relevant and more inclusive trading system.

“It’s been a long and tough road, full of uncertainty, but now it’s the dawn of a new day and the real work can begin,” she said. “The challenges facing the W.T.O. are numerous and tricky, but they are not insurmountable.”

In a news conference with reporters on Monday, Dr. Okonjo-Iweala said her initial priorities would include working with other international organizations to create lasting rules for responding to pandemics and making progress in two negotiations over fishery subsidies and digital trade.

The W.T.O.’s General Council, which includes representatives from all of the group’s 164 member countries, agreed in a meeting on Monday that Dr. Okonjo-Iweala should be the next director-general. As with many of its other decisions, the organization was required to reach a consensus on the appointment, meaning no member country could object to the choice.

The organization’s former director-general, Roberto Azevêdo of Brazil, left his post in August after announcing in May that he would be departing one year early. The members of the W.T.O. then considered eight candidates for the position.

By October, most countries had announced their support for Dr. Okonjo-Iweala. But Trump administration officials continued to express support for South Korea’s trade minister, Yoo Myung-hee, saying they believed she had more trade experience, an impasse that left the organization without a leader for several months.

After the Biden administration came into office, Ms. Yoo dropped her candidacy and the United States announced its support for Dr. Okonjo-Iweala.