This article investigates the role of media behavior in the adherence of Brazilians to the three main non-pharmacological measures (NPIs) endorsed by global health organizations against COVID-19: the use of face masks, social distancing, and frequent handwashing. Following the outbreak of a pandemic when vaccines are not yet available, the adoption of these behaviors may be the only effective measure against the threats of a new disease. Grounded in social cognitive theory, we examine the behavioral determinants of adherence to these measures in Brazil, a middle-income country marked by significant economic and informational inequalities. Brazil, one of the countries most severely impacted by the COVID-19 pandemic, was led by former President Jair Bolsonaro, who showed little regard for the use of face masks and encouraged large gatherings at political events. Our findings, based on an online survey administered to a sample of 2,771 individuals, indicate that media-related determinants such as knowledge about COVID-19, the use of social and traditional media, and belief in a conspiracy theory regarding the origin of the coronavirus play a significant role in explaining adherence to preventive measures. In contrast, other determinants such as political preferences, sociodemographic characteristics, and environmental factors play a secondary role.