Economic, social, and health crises have shaken and polarized contemporary politics. An element fueling this polarization is the dissemination of divisive topics on social media platforms. While these polarizing social media tendencies are increasingly studied, research exploring digital political communication in South America remains scarce. This study aims to analyze the electoral campaigns in Brazil, Colombia, Chile, and Peru to define the features that trigger polarized emotional reactions on Facebook. The corpus comprises a sample of 2,930 posts published by candidates and political parties during the first round of the presidential elections held in these countries between 2021 and 2022. We hypothesize that users are more likely to react in a polarized way to content focused on divisive issues. In addition, we examine how these patterns differ across countries and the influence of the level of political polarization. Finally, the role played by party-level characteristics in the emotional reactions of users is also analyzed. By means of quantitative content analysis, these questions are addressed using multilevel negative binomial regressions to identify what predicts Love and Angry reactions. The bandwagon effect seems to work positively on users’ moods since the most popular political actors receive significantly more Love reactions, irrespective of the post’s subject. In more polarized countries, there is a tendency to react more negatively to certain divisive issues, generating greater visibility of these issues on social networks and thus promoting more polarization. These findings expand knowledge about the dynamics of digital political communication in the Global South.