He was born Joseph-Désiré in Lisala, Belgian Congo. He joined the Force Publique, the Belgian Congolese army in 1949, rising to the rank of Sergeant Major. He left in 1956 and worked as a journalist and then newspaper editor. In 1958 he joined the nationalist Mouvement National Congolais (MNC). Following the grant of independence on June 30, 1960 he joined the new government as Secretary of the State for Defense. The new government was a coalition between prime minister Patrice Lumumba and the president Joseph Kasavubu, they soon started to struggle for overall power - both attempting to dismiss the other from government. On September 14, 1960 a coup d'etat overthrew Lumumba in support of Kasavubu, Colonel Mobutu was a key figure in the coup and was rewarded with rapid promotion.
In 1965, now Lieutenant-General Mobutu seized power from President Kasavubu, following another power struggle between Kasavubu and his prime minister Moise Tshombe. Mobutu declared himself president for five years. He quickly centralized power, put down an attempted coup in 1967 and was elected president in 1970. Embarking on a campaign of anti-European cultural awareness, Mobutu renamed the country the Republic of Zaire in October 1971. In 1972 he renamed himself Mobutu Sese Seko Koko Ngbendu Wa Za Banga ("The all-powerful warrior who, because of his endurance and inflexible will to win, will go from conquest to conquest, leaving fire in his wake"), Mobutu Sese Seko for short (pronounced Mobooto Sasa Sako).
Initially he nationalised foreign-owned firms and forced European investors out of the country. This precipitated a economic slump such that Mobutu was forced by 1977 to try and encourage foreign investors back. Also in 1977 he needed Belgian aid to help repulse an attack on Katanga by Katangan rebels based in Angola. Despite this he was 're-elected' in 1977, no other candidates stood. He worked hard on little but to increase his personal fortune, which in 1984 was estimated to count nearly 4 billion USD, most of it in swiss banks. This was almost equivalent to the country's foreign debt at the time, and by 1989 the government was forced to default on international loans from Belgium.
In May 1990 due to economic problems and domestic unrest Mobutu agreed to end the ban on other political parties and appointed a transitional government to build up to elections, but he retained substantial powers. However following riots in Kinshasa by unpaid soldiers, Mobutu brought opposition figures into a coalition government, but he still connived to retain control of the security services and important ministries. Factional divisions led to the creation of two governments in 1993, one pro- and one anti-Mobutu. The anti-Mobutu government was headed by Laurent Monsengwo and Etienne Tshisekedi of the UDPS. The economic situation was still dreadful and in 1994 the two groups joined as the High Council of Republic - Parliament of Transition (HCR-PT), Mobutu appointed Kengo Wa Dondo, an advocate of austerity and free-market reforms, as prime minister. Mobutu was becoming increasingly physically frail and during one of his absences for medical treatment in Europe Tutsis captured much of eastern Zaire. In mid-1997, following failed peace talks, the Tutsi rebels and other anti-Mobutu groups as the Alliance des Forces Democratiques pour la Liberation du Congo-Zaire (AFDL) captured Kinshasa. Zaire was renamed the Democratic Republic of Congo and Mobutu fled, Laurent-Désiré Kabila became the new president.
Mobutu died in September 1997 in exile in Rabat, Morocco, from prostate cancer which had been developing since 1962.