File photo: A man sells food at a market in Lagos, Nigeria, Tuesday, Feb. 7, 2023. AP
The 71-year-old southerner is from the same party as outgoing Muhammadu Buhari, the 80-year-old northerner and former army general stepping down after two terms in office.
Tinubu was declared winner of the February 25 election with 8.8 million votes and the required number of ballots across two-thirds of Nigeria's states.
Both the main opposition leader Atiku Abubakar, who came second, and outsider Peter Obi, who was third, are contesting the results in court, claiming fraud.
The electoral commission acknowledged "glitches" during the vote but dismissed claims that the process was not free and fair.
Known as a political "godfather", Tinubu campaigned saying "It's my turn" to govern the continent's largest economy, touting his experience as Lagos governor from 1999 to 2007.
Many say the astute politician has helped modernise and develop the city of Lagos, and hope he will have a similar impact on the rest of the country.
But the incoming president also faces corruption allegations, though he has always denied them, and questions around his health.
Buhari had promised to tackle corruption and insecurity but disappointed many, according to analysts, leaving behind mounting debt, rising inflation and rampant insecurity.
His presidency showed that "it is possible for an individual believed by many to be personally incorruptible to preside over an administration that is nonetheless defined by corruption and rank incompetence," said Ebenezer Obadare of the Council on Foreign Relations, a Washington-based think tank.
"With the incoming Bola Tinubu government," Obadare wrote in a blog, "Nigerians will soon find out whether a leader widely seen as corrupt can preside over a relatively malfeasance-free and reasonably competent administration."
The two men might be different in style and reputation, but they also have key similarities, from their adherence to Islam -- in a country divided between Christians and Muslims -- to their advanced age.
Buhari made repeated medical trips to the UK when he was president, while Tinubu spent time abroad during the campaign and between the election and inauguration.
With speculation about his health, eyes have turned to the incoming vice president Kashim Shettima, a 56-year-old former governor of the northern Borno state.
Once ceremonial events are over, the new government will have a lot of urgent work, starting with the economy.
One of the main challenges for oil-rich Nigeria is that it swaps crude worth billions of dollars for gasoline that it then subsidises for its domestic market.
This has caused a huge drain on revenue and foreign exchange, contributing to ballooning debt.
More than 80 million of the country's estimated 210 million people live below the poverty line, according to the World Bank, and the UN has warned that over of a quarter of those are facing acute hunger this year.
Despite thriving tech and entertainment sectors, many middle-class Nigerians are moving abroad hoping for a brighter future.
Another priority for the incoming government will be to address insecurity, which has spread like wildfire in recent years.
Troops are battling gangs of heavily armed criminals and kidnappers in central and northwestern states, oil thieves, pirates and separatists in the southeast, and a 14-year-old jihadist insurgency in the northeast.
Complicating matters, national assembly elections produced greater political plurality this year, with seven parties represented in the incoming senate and eight in the next house of representatives.
"The next administration will need to work overtime to garner consensus on the legislative agenda," said Afolabi Adekaiyaoja in a report for the Abuja-based Centre for Democracy and Development.