After eight years as governor of Lagos state, Mr Tinubu earned the nickname “godfather” after he handpicked and mentored every subsequent elected successor.
The Nigerian-born president came from humble roots, emigrating in the 1970s to the US, where he worked as a dishwasher, taxi driver and security guard to pay for his education.
He will now succeed Muhammadu Buhari, who he helped win two terms in office in 2015 and 2019.
Observers said the tight presidential election was mostly peaceful, though delays meant some voters waited until the following day to cast their ballots and opposition parties have rejected the results over claims of vote rigging.
What were the results of the election?
After millions of people across Nigeria’s 36 states took to the polls on Saturday, Mr Tinubu of the ruling All Progressives Congress party received 37 per cent of the votes, according to the country’s Independent National Electoral Commission.
His main opposition challenger, the People’s Democratic Party (PDP) candidate Atiku Abubakar, came second with 29 per cent of the votes, followed by the Labour Party’s Mr Obi with 25 per cent.
The results are likely to lead to a court challenge by the second- and third-highest finishers but the Supreme Court of Nigeria has never overturned a presidential election.
“We are rejecting the result because we feel it wasn’t fair,” Emma Ik Umeh, a member of the PDP, told Al Jazeera, adding that the party had “a lot of evidence to prove that these elections were rigged”.
Mr Abubakar previously finished second in the 2019 election and appealed those results, although his case was ultimately dismissed, and Mr Buhari also fought his past election losses for months to no avail.
Mr Tinubu thanked his supporters in the capital, Abuja, after his victory was announced on Wednesday, and addressed his challengers as he called for unity. “I take this opportunity to appeal to my fellow contestants to let us team up together,” he said. “It is the only nation we have. It is one country and we must build together.”
The election results are significantly different from those of past polls, marking the first time a president is set to take office with less than 50 per cent of the vote, according to analysts.
Mr Buhari congratulated his successor but said the election was not perfect.
“Of course, there will be areas that need work to bring further transparency and credibility to the voting procedure,” he said.
“However, none of the issues registered represents a challenge to the freeness and fairness of the elections.”
Who is Bola Tinubu?
Mr Tinubu claims to have been the influential force behind Mr Buhari winning his first term in 2015 after losing the presidential elections several times before.
Mr Tinubu’s campaign slogan was “emi lo kan” in his native Yoruba, which translates to “it’s my turn”.
According to his campaign website, he was born in Lagos in 1952, to a Muslim family from the Yoruba ethnic group, the majority in south-west Nigeria. He graduated from Chicago State University in 1979 with a degree in business administration, returning to Nigeria in the 1980s, where he worked for an oil company as an auditor before getting involved in politics in the 1990s.
He was elected governor of Lagos when military rule ended in 1999 and served two terms until 2007. His supporters say he improved roads, rubbish collection and other services in the state capital, Africa’s most populous city.
But many say the city remains deeply dysfunctional and question whether lucrative contracts afforded to some companies – in which Mr Tinubu’s close allies have a controlling interest – were value for money. The country’s former minister of state for works, Dayo Adeyeye, previously accused Mr Tinubu of “massive looting of Lagos state”.
Mr Tinubu’s support for Mr Buhari, whose government struggled to tackle Nigeria’s major economic and security problems, also did little to increase confidence in him among many of the 93.4 million registered voters.
But Mr Tinubu has sought to distance himself from the governing party he helped create. “I am not the party,” he said. “My track record should speak for me. Look at Lagos, before I came, we had dead bodies on the road, a chaotic traffic system, robbery daytime and night-time.”
Why is the result in Lagos significant?
Mr Tinubu was expected to easily win the election in Lagos, the state that is his main stronghold.
But he was beaten on his home turf by Peter Obi, 61, an anti-corruption candidate who drew a strong following among younger voters eager for change and who call themselves “Obidients”.
“You win some, you lose some,” Mr Tinubu said of the result.
His campaign called on voters to reject the two parties that have run the commercial hub for a quarter of a century.
Remi Adekoya, Polish-Nigerian writer and political analyst, said Mr Obi’s win was “the biggest shock of Tinubu’s political career”.
“This election is reshaping Nigeria’s political landscape,” he added. “The victory of Peter Obi in Lagos, the home turf of Bola Tinubu has shown that many Nigerians want a new kind of politics and that the days of godfatherism are numbered.”
Additional reporting from agencies