The decarbonization of the energy sector is among the leading global goals, and the electricity sector plays a crucial role in this low-carbon transition. However, South American countries have been underrepresented in this discussion. Understanding the particularities and the shifts in the electricity sector landscape of these countries over time and how natural resource availability, technology, and energy policies are decisive to a low-carbon transition summarizes the proposed matters in this research. This work aims to fill this gap by investigating past renewability trends in the electricity sector of five South American countries from 1990 to 2020 through five indicators. As a result, we observed a trend of low-carbon reverse transition in Argentina, Brazil, and Chile, despite the efforts and the success of renewable energy auctions, making short-term energy policy measures necessary. In Venezuela, there is a decrease in consumption and an increase in electricity generation using fossil fuels. Uruguay showed a rise in consumption and continued high use of renewables. Finally, energy policies focusing on quantifiable emission reduction should be a target of the electricity sector to achieve net zero emissions by 2050.