Mr. DeSousa has been Mayor of the Saint-Laurent borough since 2001. On the Montreal scene, he has served as a member of the Executive Committee of the City of Montreal from 2001 to 2012, in addition to being its Vice-President for the past three years. In the Montreal metropolitan area, he was a member of the council of the Montreal Metropolitan Community (CMM) from 2002 to 2012 as well as a member of its Executive Committee from 2009-2012 and 2013-2017.

In addition, because of his involvement in sustainable development and the preservation of nature, Mr. DeSousa received the Eco-Responsible Champions Award at the annual conference of the Federation of Canadian Municipalities (FCM) in 2014. That same year, the Canada Green Building Council (CaGBC) also presented him with the Public Sector Leadership Award in recognition of his significant contribution to the mission of the CaGBC and its goal of promoting green building in Canada. Finally, in 2015, the Ordre des urbanistes du Québec awarded him the Prix Jean-Paul-L’Allier, which honors a Quebec elected official who has distinguished himself by his vision, leadership and achievements in urban planning and development.