This was confirmed by one of Buhari’s media aides, Bashir Ahmaad, on Twitter on Thursday night.
The president initially nominated Nigeria’s permanent representative to WTO, Yono Frederick Agah, for the same role.
However Agah’s candidacy has now been withdrawn.
The election will hold in Geneva, Switzerland in 2021.
The four-year term would then run from 2021 to 2025, after the former director-general of the organisation, Roberto Azevedo, stepped down a year to the end of his second term.
Okonjo-Iweala presently chairs the Global Alliance for Vaccines and Immunization (GAVI) and also sits on the board of Twitter.