Nutritional warnings have been recently introduced as a new front-of-pack nutrition labelling scheme. Its particular goal is to facilitate the identification of products with excessive content of nutrients, given these are associated with non-communicable diseases. The aim of the present study was to evaluate the influence of nutritional warnings on consumers’ choice of a snack in a choice experiment involving real products. A total of 199 participants were asked to evaluate a series of bread images on a computer screen using eye-tracking glasses. Once they finished the task, they were invited to help themselves a snack from a shelf as a compensation for their participation in the study. A total of 15 snack products with different nutritional composition were included on the shelf. Participants were randomly divided into groups: one that made their choice from a shelf containing products that did not include front-of-package nutritional information, whereas the other chose among products that featured nutritional warnings. Participants in both experiments invested an average of 14 s to select their product. When products were presented with warnings, 50% of the participants fixated their gaze on the warnings during the choice task. Significant differences in the frequency of selection of the products (p = 0.002) were found between the groups. When the warnings were present, participants chose products with fewer warnings and lower average sodium, saturated fat, and sugar content (p < 0.001). These findings confirm the potential of nutritional warnings to encourage more healthful food choices.