Muhammadu Buhari, has issued a defiant vow against militants Boko Haram, saying they would "soon know the strength of our collective will".
The president-elect also vowed to tackle corruption, which he described as an "even greater evil".
Gen Buhari won the election beating President Goodluck Jonathan by 2.5 million votes.
World leaders congratulated Gen Buhari and hailed Nigeria's democratic spirit.
