The son of a Teke mother and Fang military officer,[5][3] Oligui was born in Haut-Ogooué Province, Gabon, which was regarded as a stronghold of the ruling Bongo family.[6] Via his mother, he is a cousin of former President Ali Bongo.[7] Oligui was mostly raised by his mother and her family in Haut-Ogooué,[6][8] and studied at Omar Bongo University.[9]
In October 2018, he was recalled to Gabon where he replaced President Ali Bongo's half-brother Colonel Frédéric Bongo at the head of the intelligence service of the Republican Guard.[6][12] He was then promoted to Brigadier general in April 2019.[6] In 2021 he restarted Operation Mamba, a campaign to arrest corrupt officials.[13]
He took over the head of the Gabonese Republican Guard in April 2020, replacing General Grégoire Kouna, a cousin of then President Ali Bongo.[14] He significantly increased the Special Interventions Section (SIS), a special unit placed under the direct authority of the President, increasing it from around thirty to more than 300 elements.[12] He also composed a song which included the line "I would defend my president with honour and loyalty".[11]
According to a 2020 Organized Crime and Corruption Reporting Project (OCCRP) investigation, he owns several properties in the United States worth more than $1 million[15] and also helped expand the Bongos' overseas businesses. Asked about these dealings, he said they were a "private affair".[11]
Officials of Bongo's regime and others who had interacted with Oligui described him as "fairly intelligent man, easy to talk to", "discreet" and "a man of consensus" who is "very appreciated by his men".[6]
In an interview with Le Monde later in the day, he referred to Bongo as "retired", and said that the military had staged the coup due to discontent that had been growing in the country since Bongo's stroke in 2018, his decision to run for a third term, the disregarding of the country's constitution and the conduct of the election.[21] His appointment as interim president was later confirmed by other generals,[22] and he was formally sworn in as "transitional president" at the Presidential Palace on 4 September.[23][24] In his inaugural address, he pledged to hold "free, transparent" elections but did not give an exact date as to when. He also announced the formation of a new government in the coming days and proposed new electoral legislation, a new penal code, a referendum on a new constitution, and the release of all political prisoners.[25]
In October 2023, Oligui announced that he would give up his salary as president and rely instead on his wages as commander of the Republican Guard.[26]