A smooth handover would be a rare bright spot for a country blighted by widespread poverty and Islamist violence that has killed hundreds of civilians and soldiers in the last year alone.
Niger has experienced four coups since gaining independence from France in 1960.
It would also contrast with the Ivory Coast and Guinea, whose presidents this year used constitutional changes to extend their tenures to three terms, raising fears of a democratic backslide in West Africa.
"It's extremely important for us because we are seen as the champion of the coup d'état," said 50-year-old Massaoudou Abdou who voted in a school in the town of Maradi in southern Niger.
"In 60 years of independence, this is the first time," he said, referring to the passing of power from one elected president to another.
Former interior minister Mohamed Bazoum, the ruling party's candidate, is the overwhelming favorite to succeed President Mahamadou Issoufou, who is stepping down after two five-year terms leading the country of 23 million.
Bazoum, 60, has promised continuity with Issoufou's policies, while also vowing to clean up pervasive corruption.
Élection présidentielle du 27 décembre 2020.Toutes les étapes de la campagne électorale en résumé vidéo. #SaïBazoum #RenaissanceActeIII #Consolider & #Avancer #VOTEZ_MohamedBazoum pic.twitter.com/8u8aC4haRP— Mohamed Bazoum (@mohamedbazoum) December 25, 2020
"If I am lucky enough to win this election, you will have chosen someone who is ready from day one," he said in a campaign video.
Niger has suffered repeated attacks near its western borders with Mali and Burkina Faso from militants linked to al-Qaeda and Islamic State, including one in January that killed at least 89 soldiers. Hundreds of miles to the east, near its southeastern border with Nigeria, it faces attacks from Boko Haram.
More than 40% of Niger's population lives in extreme poverty, and the COVID-19 pandemic has slowed growth to a crawl, compounding the effects of climate change and low prices for top export uranium.
Bazoum faces 29 other candidates, who will hope to force a second round by denying him an outright majority.
Hama Amadou, who finished runner-up in the last election, was barred from running because of a criminal conviction, leaving the opposition without an obvious figurehead.But last week, Amadou's party called on its supporters to turn out for Mahamane Ousmame, who was president from 1993-1996, which could spur some to turn out and vote.