Milongo came from today's Pool region of the former French colony. After the country's independence, he worked in financial management. Later he was a consultant for financial and economic issues, the Prime Minister Lopès and Goma. In the 1980s he became the director at the World Bank.
In the last phase of the reign of the incumbent since 1979 President Denis Sassou Nguesso, he was on June 8, 1991 Prime Minister of the transitional government that would lead the country to democracy. In the first round of presidential elections on August 8, 1992, he reached as a candidate of the party Union pour la démocratie et la république ( UDR) with 10.18 % of votes in fourth place and retired. Winner in the second round was the former Prime Minister Pascal Lissouba. Milongos term as Prime Minister ended on 2 September 1992.
From 1994 to 1997 he was President of the Parliament. This year Lissouba was overthrown by the returned from exile Sassou Nguesso after several months of civil war.
Milongo initially wanted to compete in the presidential election of 10 March 2002 but withdrew his candidacy shortly before the vote because of alleged unfair conditions as before some of the other candidates back. Sassou Nguesso incumbent won with 89.41 % against the little-known six remaining candidates. Milongo was still President of the UDR, member of Parliament and one of the leaders of the opposition against Sassou Nguesso.
Family and death
Milongo was married and the father of seven children. He died in the early morning of 23 July 2007 at the age of 71 in a hospital in Paris.