File photo: Bola Tinubu of the All Progressives Congress, center, accompanied by his wife Oluremi Tinubu, right, leaves the party s campaign headquarters after winning the presidential elections in Abuja, Nigeria, Wednesday, March 1, 2023. AP
On Monday, what Tinubu called his "lifelong" goal became reality as he was sworn in after winning presidential elections in February.
The two-time Lagos governor succeeds President Muhammadu Buhari, a former army general he had bragged of helping to put into power.
The 71-year-old takes the helm of Africa's most populous nation and biggest economy.
But it is also a troubled giant facing challenges from entrenched poverty to widespread insecurity, and Tinubu himself faces concerns about his health and corruption allegations.
Tinubu's ruling All Progressives Congress (APC) party faces accusations of voter fraud, although electoral officials and the APC have dismissed those claims.
Tinubu is often referred to with the chieftain's honorific of "Jagaban," and his supporters say his skills in modernising Lagos will have a similar impact on the rest of the country.
A Muslim born in Nigeria's Yoruba-speaking southwest, Tinubu trained as an accountant in the United States and worked for several US companies, including as a treasurer at oil giant ExxonMobil.
He was a political activist before becoming a senator and later governor of Lagos State from 1999 to 2007.
During his activist days, he was hounded into exile by military dictator Sani Abacha along with scores of others for campaigning for a return to democratic rule in 1999.
Described by his allies as a political strategist, he co-founded and financed the Alliance for Democracy, which later became the Action Congress of Nigeria, and then helped form the ruling APC.
He was instrumental in bringing together factions of the party, pushing Buhari to victory in 2015 and ending 16 years in power for the rival Peoples Democratic Party (PDP).
The election of Buhari, the first opposition victory in the country, as well as his 2019 re-election were partly attributed to Tinubu's political influence.
In a mark of his staying power, Tinubu kept a tight grip over the governorship of megacity Lagos, having a hand in choosing his successors since leaving office.
Tinubu spent years building his power base, from market cooperatives and transport unions in Lagos, to a nationwide network of contacts.
His influence in the southwest irked some would-be political operatives who missed out on top jobs, and Tinubu has been criticised as dictatorial and undemocratic in style.
"Tinubu has a very aggressive, very solid political machine," said Dapo Thomas, a political science lecturer at Lagos State University.
If Tinubu's political power has often been controversial, so too have his financial dealings.
He is believed to be one of Nigeria's richest politicians and after leaving office he was accused of corruption, money laundering and operating more than a dozen foreign bank accounts. He has always denied any wrongdoing.
On the campaign trail, he was attacked for a 1993 US court filing that cited a "drug-related seizure of property" from his US bank account.
The source of his wealth is unknown but he has interests in a number of business ventures, from media and aviation, to tax consultancy, hotels and real estate holdings.
Outgoing Information Minister Lai Mohammed, who was Tinubu's former chief of staff, insisted he was among the shrewdest of political operators.
As president, Tinubu will face difficult decisions from removing costly fuel subsidies to addressing rising poverty and rampant insecurity.