The COVID-19 pandemic caused an unprecedented political, economic, and social impact, aggravating global food insecurity (FI). We measured the prevalence and severity of FI before and during the pandemic in South America, to understand its impact and how this impact was distributed across socio-economic groups. On total, we surveyed 18,997 households across seven countries on the prevalence and severity of FI before and during the pandemic using the Food Insecurity Experience Scale (FIES) developed by the Food and Agriculture Organization (FAO). Before the pandemic, approximately 4.5% (19.39 million) of the South American population experienced Moderate, while 0.6% (2.58 million) faced Severe FI. At this time, Venezuela had the highest prevalence of Moderate FI (9.7%), and Peru had the highest Severe FI (1.1%). The pandemic had a profound impact in South America, upping Moderate FI to 16.9% (+12.4%) and Severe FI to 2.7% (+2.1%). This increase represents an additional 53.4 and 9.04 million people, respectively. Peru experienced the most substantial increase in both Moderate (+23.9%) and Severe (+4.6%) FI. Low-income households (less than two minimum wages per month) had a higher likelihood of suffering from FI, with Uruguay's and Peru's low-income families showing the biggest increase in Moderate (+40.4%) and Severe FI (+9.1%), respectively. This study highlights the staggering impact of the pandemic on food insecurity across South America, underscoring the urgent need for effective interventions on public policies.