In a series of messages on Twitter, Mr Dangote said that a vote for Mrs Okonjo-Iweala is a step in the right direction.
“A vote for her by all is a step in the right direction. I fully endorse the candidature of Okonjo Iweala-Iweala to lead the WTO,” the billionaire wrote.
“In these challenging times, WTO needs the renowned skills and tested experience of Dr. Ngozi Okonjo-Iweala to lead the organisation through identified obstacles and strengthen its position as the prime facilitator of international trade.”
The endorsement comes ahead of the second phase of the selection process on September 7, 2020.
Mrs Okonjo-Iweala sits on the board of Twitter and chairs the Global Alliance for Vaccines and Immunisation (GAVI).
For the WTO top job, she is contending against seven other candidates from Mexico, Egypt, Moldova, Republic of Korea, Kenya, UK and Saudi Arabia.
The candidates were nominated by their respective governments to succeed the incumbent Director-General, Roberto Azevêdo, who has since stepped down on 31 August.
In July, Mrs Okonjo-Iweala stressed the need for the World Trade Organisation (WTO) to elect a credible candidate based on merit for the position of Director-General.
“Choosing a Director-General for WTO should be on merit. The best person should be chosen to lead an institution that’s having challenges,” she said.
“If it happens to be a woman, great. If it happens to be an African, it’s also great. It should be based on merit.
“The WTO needs leadership and I’m someone with a strong managerial capability with the ability to forge consensus and reforms.
“These bundles of qualities in addition to my leadership quality is what I’m bringing to the WTO,” she added.