Muhammadu Buhari was sworn in as Nigeria's new head of state on Friday after he became the first opposition candidate to defeat a sitting president in a landmark election earlier this year, France 24 reported.

During his swearing-in ceremony, Buhari pledged to uphold the constitution and laws of Africa’s most populous nation.

The 72-year-old takes charge of Africa's most populous nation, which is facing crises on several fronts, from severe economic turmoil to Boko Haram's still-raging Islamist insurgency.