Challenger Muhammadu Buhari has won Nigeria's presidential election by 2.57 million votes, official results show, defeating incumbent Goodluck Jonathan in the first democratic change of power in Africa's most populous nation.
The victory on Wednesday writes a new chapter in the country's often turbulent history after six military coups since independence in 1960 and 16 years of unbroken civilian rule by Jonathan's party.
The gripping contest also capped a remarkable transformation for 72-year-old former army general Buhari, who led a tough military regime in the 1980s but now describes himself as a "converted democrat".
Thousands spilled onto the streets of northern Nigeria's biggest city, Kano, in celebration, shouting campaign slogan "Sai Buhari" ("Only Buhari") as he took an unassailable lead with one state to declare.
Many brandished brooms, Buhari's party symbol, with which they have pledged to sweep away years of government waste and corruption.
In another northern city of Kaduna - the scene of rioting after the 2011 presidential election - supporters of his All Progressives Congress (APC) chanted: "Change! Change!"
The Independent National Electoral Commission (INEC) said Buhari won 15,424,921 votes, or 53.95 per cent, of the 28,587,564 total valid ballots cast.
Rival Jonathan, 57, of the Peoples Democratic Party (PDP), won 12,853,162 votes (44.96 per cent) in the election held Saturday and Sunday.
INEC chairman Attahiru Jega said: "Muhammadu Buhari, of the APC, having satisfied the requirement for the law and scored the highest number of votes, is hereby declared the winner and is returned elected."
The election was hit by glitches in new voter technology and claims of irregularities, after being delayed by six weeks due to concerns of attacks by Boko Haram insurgents.
Political commentator Chris Ngwodo said the victory had "instigated the supremacy and primacy of the electorate" in a country where elections had generally been a foregone conclusion for the incumbent.
"The dynamics between the governed and government has changed for good," he said.
Buhari won because, backed by a strong and well-organised party machine, he had managed to secure national support in a nation split between a largely Muslim north and mainly Christian south, Ngwodo added.
Jonathan conceded in a telephone call to Buhari even before the final results were declared, earning him praise from politicians of all stripes.
"I promised the country free and fair elections. I have kept my word," he said later, urging disputes over the results to be settled in court rather than on the street.
"Nobody's ambition is worth the blood of any Nigerian," he added.
