About 7.4 million people have registered to vote for the new president, the same as in the legislative elections.
Nigeria is voting in the first transfer of power between two elected presidents in a non-violent democracy.
Former Interior Minister Mohammad Bazou is the ruling party’s candidate, leading President Mahamadou Issoufou after 50 years and leading the desert to 23 million.
Bazoum, 60, has vowed to continue Issoufou’s policies and to crack down on widespread corruption.
He is facing 29 other candidates hoping to win a second term by a landslide.
Hamas Ahmadinejad, who ended the race in the last election, has left the opposition party without a prominent leader due to his conviction. He was expelled from the party until last week He called on his supporters to elect Mahamane Ousmane, who served as president from 1993 to 1996.
An estimated 7.4 million people voted for the new president, the same as in the legislative elections.
The campaign has been overshadowed by the security situation in a country that has suffered repeated attacks on the border areas of Mali and Burkina Faso by al-Qaeda and ISIL (ISIS)-linked fighters. Boko Haram is facing attacks near the border with Nigeria.
Hundreds of soldiers and civilians have been killed in the past year.
Economic conditions are also important. More than 40% of the population lives in extreme poverty. The COVID-19 epidemic has slowed growth due to the effects of climate change and lower prices for its top export, uranium.
A peaceful transfer of power is a milestone for Nigeria. France has experienced four coups since independence in 1960.
Authorities said the army was deployed for Sunday’s election.
“Intermittent attacks do not prevent the election process,” a spokesman said on Thursday.