Muhammadu Buhari is the first Nigerian to defeat a sitting president through the ballot box, putting him in charge of Africa's biggest economy.
Buhari was declared the winner after he gained 2.7 million more votes than his rival, incumbent President Goodluck Jonathan.
Buhari managed to secure more than 25 percent of votes in 24 states, ruling out a run-off vote.
To win the election, Buhari had needed more than 50 percent of the total votes nationally - and take at least 25 percent of the vote in two thirds of the states.
Jonathan has publicly conceded defeat and conveyed his "best wishes" to the president-elect.