Background The Nutri-Score, a front-of-pack nutrition label, has been adopted in 2017 in France but its impact on low-income populations is unknown, and they are more at risk of having unhealthy diets. The present study assessed the effects of the Nutri-Score on the nutritional quality of purchasing intentions among low-income individuals, compared with the current French labelling situation: references intakes (RIs) and no label, using a three-arm parallel-group randomised controlled trial. Methods Low-income active adults from the NutriNet-Santé cohort (household income below €1200/month) were asked to perform a shopping task in an experimental online supermarket after being randomised in one of the three conditions (Nutri-Score, RIs or no labelling). The main outcome was the overall nutritional quality of the virtual shopping cart, assessed with the French-modified Food Standards Agency Nutrient Profiling System (FSAm-NPS), and secondary outcomes were the nutrient content of the shopping carts. 524 subjects were randomised, and 336 included in the analyses. Results The Nutri-Score resulted in the highest overall nutritional quality of the shopping cart, as reflected by a FSAm-NPS score (1.86 (SD 3.59) points) significantly lower (reflecting higher nutritional quality) than the RIs (3.21 (SD 4.14) points, p≤0.05) but not significantly lower than no label (2.60 (SD 3.09) points, p=0.3). The Nutri-Score also resulted into significantly lower contents in calories and saturated fatty acids in the shopping cart, compared with the RIs only (p≤0.05). Conclusion The implementation of the front of pack nutrition label Nutri-Score, adopted in France and in different European countries, appears to have the potential to encourage purchasing intentions of foods from higher nutritional quality among low-income individuals, compared with the RIs label promoted by food manufacturers. Trial registration number: NCT02769455