Abstract Objective This study assessed the impact of nutrient warning labels on product selection and ability to correctly identify less healthy products, among other outcomes, in Colombia. Methods We conducted an online randomized experiment among 8,061 Colombians in October 2020. Participants were assigned to a condition: nutrient warning, guideline daily amounts (GDA), Nutri-Score, or no-label. First, participants viewed two fruit drinks labeled according to their assigned condition, one with added sugar and one without, and indicated which they would prefer to buy and which was higher in sugar. Next, they viewed four food products with their assigned condition and answered questions. Finally, they selected which label type would most discourage them from consuming a specified ultra-processed food. Results Fewer participants in the nutrient warning condition (20%) preferred to buy the added sugar fruit drink compared to 24% in the GDA condition (p<.01), 29% in the no-label condition, and 33% in the Nutri-Score condition (both, p<.001). More participants who saw the nutrient warning (88%) correctly identified the fruit drink higher in sugar compared to those who saw no-label (68%) or Nutri-Score (65%) (both, p<.001). In the GDA condition, 91% correctly identified the fruit drink higher in sugar compared to the nutrient warning condition (p<.01). Most participants (72%) selected the nutrient warning label as most discouraging. Conclusions Nutrient warning labels are a promising policy strategy to prevent obesity and diet-related non-communicable diseases in Colombia. Future research should assess nutrient warning labels’ impact on actual food purchases in Colombia. Trial Registration: NCT04567004