Bola Ahmed Tinubu thanks his supporters after he was declared winner in Nigeria's presidential election, at the Party's campaign headquarters, in Abuja, Nigeria March 1, 2023. (Reuters)

The 71-year-old southerner Bola Tinubu succeeds the 80-year-old northerner Muhammadu Buhari as Africa's most populous nation faces a slew of economic and security challenges, as he was sworn in as Nigeria's new President.

"As president of the Federal Republic of Nigeria I will discharge my duties and perform my functions honestly to the best of my ability, faithfully and in accordance with the constitution," Tinubu said, in a live broadcast from the capital Abuja's Eagle Square

Foreign leaders and representatives present during the event included South African President Cyril Ramaphosa, Rwandan President Paul Kagame, and Ghanaian President Nana Akufo-Addo, as well as delegations from the United States, the United Kingdom, and China.

Kashim Shettima was sworn in as Vice President, taking over from Yemi Osinbajo.

The governing party duo were proclaimed election victors on February 25, after receiving 8.8 million votes and casting the requisite number of ballots in two-thirds of Nigeria's states.

The results are being challenged in court by the major opposition leader, Atiku Abubakar, who finished in second, and outsider Peter Obi, who came in third.

The electoral commission recognized "glitches" in the voting process but refuted charges that it was not free and fair.

Dubbed a political "godfather", Tinubu campaigned by saying, "It's my turn" to govern Nigeria, Africa's biggest economy.

However, the new President is now facing corruption charges, which he rejects, as well as health concerns.