Okonjo-Iweala, the first woman and the first African to head the WTO, was the only candidate in the race, and had been all but assured a second term.
The organisation's 166 members "today agreed to give incumbent Ngozi Okonjo-Iweala a second term as director-general," the WTO said in a statement.
The 70-year-old Nigerian's reappointment was approved by consensus during a special meeting of the organisation's General Council, held behind closed doors, the WTO said.
Her current term ends in August 2025, and the appointment process for the next mandate had initially been scheduled to take months.
But with Okonjo-Iweala the only candidate, African countries called for the process to be speeded up, officially to facilitate preparations for the WTO's next big ministerial conference, set to be held in Cameroon in 2026.
The unstated objective is to "accelerate the process, because they did not want Trump's team to come in and veto her as they did four years ago", said Keith Rockwell, a senior research fellow at the Hinrich Foundation.
The common practice of appointing directors-general by consensus made it possible in 2020 for Trump to block Okonjo-Iweala's appointment for months, forcing her to wait to take the reins until after President Joe Biden entered the White House in early 2021.
Fear of a void
The overwhelming support for Okonjo-Iweala's second term came "not so much (because) everyone loves Ngozi", a source close to the discussions told AFP.
Rather, members were "worried that if she doesn't get reinstated, then it's possible that the administration in Washington would slow things (or) block other contenders", leaving a void at the top, the source said.
"The alternative of no-one leading the organisation is unacceptable to them."
Rockwell, a former WTO spokesman, told AFP that speeding up Okonjo-Iweala's reappointment "creates tensions in the relationship with the United States, for sure -- tensions which would probably have been there under any circumstances, but now this raises the stakes".
During Trump's first term, the WTO faced relentless attacks from his administration, which crippled the organisation's dispute settlement appeal system, and also threatened to pull the United States out of the organisation altogether.
And Trump has already signalled he is preparing to launch all-out trade wars, threatening to unleash a flurry of tariffs on China, Canada and Mexico on his first day in office on January 20.
"The festival of tariffs announced to date shows that he has no intention of following any rules," said Elvire Fabry, a researcher at the Institut Jacques Delors think-tank.
"The United States would not even need to withdraw from the WTO," she told AFP. "They are freeing themselves from the WTO rules".
In this context, the WTO chief will have "a firefighter role", she said.
'Very difficult'
It will be a question of "saving what can be saved, and making the case that there is no real alternative to the WTO rules", said another source close to the discussions on speeding up Okonjo-Iweala's reappointment.
"It will be a very difficult mandate, with little certainty about what will happen."
Rockwell noted that the WTO's problems were not solely linked to Washington.
"It is a time right now in which application of the WTO rules has deteriorated," he said.
"You can't blame all of this on the United States. That's true of many other members as well."
Dmitry Grozoubinski, author of the book "Why Politicians Lie about Trade", agreed.
"Governments are increasingly turning to trade measures to address issues like national security, environmental competition, and re-industrialisation, and policymakers aren't as moved as they once were by arguments that their ideas violate the letter or spirit of WTO commitments," he told AFP.
"If president-elect Trump makes destroying the WTO a priority," he said, the organisation's "options will be limited as the institution is not built to withstand overt demolition from within its membership".
Since taking the WTO reins, Okonjo-Iweala has tried to breathe new life into the fragile organisation, pushing for fresh focus on areas like climate change and health.
But pressure is growing for WTO reform, in particular of the moribund appeals portion of its dispute settlement system, which collapsed during the first Trump presidency as Washington blocked the appointment of judges.
