A Muslim and a native of the north of Côte d'Ivoire, Koulibaly was born at Azaguié-Gare and studied economics, becoming an economist and economics professor. Under the transitional military regime of Robert Guéï, Koulibaly served in the government as Minister of the Budget from 15 January 2000 to 18 May 2000, then as Minister of the Economy and Finances from 18 May 2000 to January 2001. When Guéï was ousted following the disputed results of the October 2000 presidential election and FPI leader Laurent Gbagbo was sworn in as president, Koulibaly retained his post as Minister of the Economy and Finances, while gaining the role of Government Spokesman. He remained in those posts until 15 January 2001.