The event, which is holding at the Eagle Square in Abuja, will see 2,340 delegates queuing to choose their preferred presidential candidate.
In the lead-up to the exercise, 28 presidential hopefuls had picked the nomination and expression of interest forms, but five of them later pulled out.
Twenty-three aspirants later appeared before the APC presidential screening committee led by the party’s former chairman, John Odigie-Oyegun.
The run-up to the special convention, which is billed to run till Wednesday, had been marred by intrigues over the zoning of the presidential ticket and consensus candidacy.
While a consensus candidate was said to have emerged on Monday, President Muhammadu Buhari on his part said the delegates should be allowed to decide the party’s presidential flagbearer.
The northern APC governors also canvassed for the party’s candidate to come from the southern part of the country.