The Treaty of Asunción, signed in 1991, laid the foundations for the creation of a regional integration project between Argentina, Brazil, Paraguay and Uruguay: the Southern Common Market (Mercosur). The formal re-democratisation that took place during the 1980s was a coinciding factor between these four nations. It is no coincidence that democracy has been an essential condition for the regional integration process since the bilateral rapprochement between Argentina and Brazil in the second half of the 1980s. The aim of this paper is to discuss the presence of the concept of democracy and the concern for the promotion and protection of human rights in the evolution of the Mercosur regional integration process, emphasising official documents produced by the bloc, their historical contexts and applications: controversial episodes such as the suspension of Paraguay after the impeachment of President Fernando Lugo, followed by the admission of Venezuela, both in 2012, are also analysed.