He received a diploma from the Collège coopératif of Paris, a diploma from the School for Advanced Studies in the Social Sciences, a bachelor's in arts (English), and a doctorate from the École pratique des hautes études with a thesis entitled "Moorish Traditionalism and Rural Modernisation in Senegal: Contribution to the Study of Links between Socialism and Islam in Under-Developed Countries.

"[2] From December 1965 to June 1966, Sy was professor of the sociology of development and director of studies at the École nationale d'économie appliquée [fr] (ENEA) in Dakar, Senegal.

In July 1978, Sy returned to Senegal to take up the position of director of École nationale d'économie appliquée (ENEA) in Daker.

He left Senegal in July 1988 to become personal foreign affairs advisor to Mobutu Sese Seko, President of Zaire.

Between September 1996 and February 1997, he was the principal political advisor of the Special Representative of the Secretary General of the United Nations in Burundi.

From October 2001 until November 2002, Sy was president of the administrative board of the Banque Internationale pour le Commerce et l'Industrie du Sénégal (BICIS).

Sy was named president of the administrative board of the Société africaine de raffinage [fr] (SAR) on 18 November 2009.