Democratically, it is hard to pinpoint an individual as the longest serving President of the Federal Republic of Nigeria as the Constitution of the country only allow an individual to be President of the country for a two term maximum of eight years, altogether.

Although Nigeria had had Presidents who ruled for less than four years, like Late President Umaru Musa Yar'adua who died after about three years in office and former President Goodluck Jonathan who happened to be the Vice President to Late Umaru Musa Yar'adua and lost his second term election after ruling for about five years, completing about one year left for his former boss, Yar'adua and his four years presidency after winning 2011 presidential election.

Both Presidents Olusegun Obasanjo and Muhammadu Buhari spent their eight years separately; Obasanjo (1999 to 2007) and Buhari (2015 to 2023). President Bola Ahmed Tinubu is currently on the second years of his first tenure but according to the Constitution, the maximum he can spend is two term of eight years.

Quietly amazing, recalling that Obasanjo was a former Head of States ruling Nigeria between February 13, 1976 and October 1st, 1979 which is about 3 years 7 months and 17 days of ruling as Nigeria Head of States.

Also, Muhammadu Buhari waa a former Head of States ruling between December 31st, 1983 and August 7th, 1985 was the head of the nation for 1 year 7 months and 6 day.

Although Presidency is a term that is known to the Democracy, it is called Head of States under the Military Rule but the two have the same mandates even though under different administrative settings, so we can determine who is the longest serving Nigeria leader by merging the tenures spent as the Head of States and the President.

In this scenario,  Chief Olusegun Obasanjo is the longest serving Nigeria President (leader), leading the country for 11 years 7 months and 17 days.