Judges dismissed claims made by the opposition leader, who alleged voter fraud, argued that the electoral authority broke the law, and that Tinubu was ineligible to run for office.
"This petition is hereby declared unmeritorious," said one of the judges after over six hours of reading through a detailed judgement.
The court was also set to read its judgement on the second major opposition claim, filed by the People’s Democratic Party, PDP, led by former Vice President Atiku Abubakar who shared Obi’s concerns about the election outcome.
Abubakar called the vote a "rape of democracy" and his party says it presented proof that INEC broke electoral law in its transmission of results, and of Tinubu's failure to meet constitutional requirements.
Prior to the hearing of the case presented by LP and PDP, judges dismissed a smaller opposition claim to annul Nigeria’s elections.
The verdict to uphold Tinubu’s presidency will likely head to an appeal in the Supreme Court, which is yet to overturn a presidential election in Nigeria since the West African nation returned to civilian rule after a military government in 1999.
The ruling All Progressives Congress, APC, dismissed claims by the opposition of wrongdoing and appeared confident before the decision passed by the judges.
Speaking to Channels TV, Ajuri Ngelale, Nigeria's presidential spokesperson said Tinubu has "faith and confidence in the judiciary."
"He (Tinubu) believes that the mandate which Nigerians freely gave to him during the elections will stand," Ngelale said.
"He is not worried, simply because he knows he won the election," he added.
Tinubu took office at the end of May and has quickly introduced a set of reforms the government says will help put Africa's largest economy back on track.
He is currently in India to participate in the G20 summit where he is seeking foreign investment.
The 2023 election was one of the most contested in the country's modern history, thanks in part to the emergence of a major third-party candidate to challenge the dominance of Tinubu's All Progressives Congress (APC) and the PDP.
Labour's Obi looked to appeal to younger voters who said they were looking for an alternative to the old-guard candidates.
To improve transparency, the Independent National Electoral Commission (INEC) introduced biometric technology and IReV, a central database for uploading results in real time.
INEC acknowledged "glitches" but dismissed claims the vote was not free and fair.
The court ruling comes as Nigerians struggle with a rising cost of living after the government ended a fuel subsidy program that kept petrol prices low and also freed up the naira currency.
Government officials say the policies are needed to revive the economy, calling for patience and supplying state governments with funds to help offset the impact.
Tinubu's government is also tackling huge security challenges, from jihadists still fighting a long war in the northeast to intercommunal clashes and kidnap gangs operating in other regions.