According to the results from Saturday's vote declared by the Independent National Electoral Commission (INEC), APC won the governorship in 15 states -- Lagos, Sokoto, Katsina, Jigawa, Gombe, Kwara, Niger, Yobe, Nasarawa, Cross River, Ebonyi, Ogun, Benue, Kaduna and Borno.
The main opposition Peoples Democratic Party (PDP) won seven -- Plateau, Bauchi, Oyo, Delta, Rivers, Akwa Ibom and Zamfara states.
The New Nigeria People's Party (NNPP) emerged victorious in Kano, northern Nigeria's largest state.
The APC's Babajide Sanwo-Olu scored a landslide re-election as Lagos governor.
In the key northeastern region of Adamawa - which could see the election of Nigeria's first woman governor - the results were declared "inconclusive" as the number of voters unable to cast their ballot was greater than the margin between the two frontrunners.
INEC will set a new date for elections in areas of Adamawa where people had been unable to vote, and afterwards then declare the state-wide result.
More results were expected on Tuesday.
Elections were held to choose governors in 28 of Nigeria's 36 states and state assembly lawmakers. Governors in the remaining eight states had earlier been chosen in by-elections due to court rulings.
The local elections came three weeks after the candidate of the ruling All Progressives Congress (APC), Bola Tinubu, won a presidential ballot that rivals said was massively rigged.
Local and international observers said the latest poll was marked by apathy after disappointments in the presidential election but also by intimidation tactics, vote buying and violence.
EU mission Chief Observer Barry Andrews on Monday said Nigerians' expectations for Saturday's election were not met in many parts of the country.
"Many were disappointed and we witnessed voter apathy that is a clear consequence of failures by political elites and, unfortunately, also by INEC," he said.
