Résumé : Environmental concerns have taken the frontline of international discussions and meetings. As the nature of the causes of environmental degradation was discovered to be increasingly complex, the essence of the discussions was also becoming exponentially more intricate. More actors and therefore, different interests and realities, were introduced to the scenario. This is the context of emerging powers which were willing to participate in the international environmental agenda by moving forward their national rights and needs to develop in the economic and social spheres. Against this backdrop, the concept of sustainable development arises; a term that has proved to be highly political. This research aims at assessing the role of developing countries in transforming the concept of sustainable development, taking Brazil as the perfect case study because it gathers crucial elements such as its mega-diversity condition, its economic and social development and its political relevance in the regional and international scenarios. This research is centered on the study of how Brazil, as an emerging country, has defended and evolved in the defense of the balance between the economic, social and environmental pillars of the term sustainable development at the international conferences that dealt with the defense and protection of the environment. The thesis presents a three-phase qualitative assessment of the hypothesis of the transformative role of Brazil in the context sustainable development during three major international scenarios: The United Nations Framework Convention on Climate Change, the Commission on Sustainable Development, and the Convention on Biological Diversity.