Mrs Okonjo-Iweala was confirmed DG of the trade body according to a statement by the WTO on Monday.
Mrs Okonjo-Iweala was confirmed DG of the trade body in a statement by the WTO on Monday.
The United States government had last week announced its endorsement of Mrs Okonjo-Iweala for the top job.
It became clear earlier on Friday that Mrs Okonjo-Iweala, a former World Bank executive, would likely clinch the coveted post after her final challenger to the position, South Korean Trade Minister and candidate, Yoo Myung-hee, announced her withdrawal.
Ms Yoo made the decision after discussions with the U.S. and other major nations, a statement from Korea's trade ministry said on Friday.
She also took various issues into account "comprehensively" including the need to revitalise the multilateral organization, reports said Friday.
Last October, the World Trade Organisation selected Mrs Okonjo-Iweala and Ms Yoo to advance to the final round in the race to lead the Geneva-based trade body.
Mrs Okonjo-Iweala is, however, largely considered the shoo-in among experts and influential figures within the WTO.
Mrs Okonjo-Iweala was Nigeria's finance minister during the tenures of former presidents Olusegun Obasanjo and Goodluck Jonathan. She has experience working at international governance bodies as a former managing director of the World Bank and as a chairman at the Global Alliance for Vaccines and Immunization.
With Mrs Okonjo-Iweala's emergence, the WTO now has its first female director-general in its 25-year history.