Objective: To characterize the presence of nutrient claims on the front-of-pack labels of ultra-processed foods directed at children and gain insight on children' views about the presence of marketing strategies and nutrient claims on labels of ultra-processed foods. Methods: Analysis of images (front panel, nutrition facts table, and ingredients list) of labels from 535 packaged foods with marketing strategies directed at children obtained in an audit-type survey conducted at a Brazilian large supermarket store. Food products with ultra-processed characteristics were identified, and the nutrient claims were quantified and described. Focus groups were conducted with children aged 8-10 years. Results: A total of 472 (88.0%) of the 535 packaged foods directed at children were classified as ultra-processed. Of these, 220 (46.6%) had one or more nutrient claims on their front-of-pack label (n=321), most (n=236, 73.5%) claiming the presence/increased quantities of vitamins and minerals. The most common 'free/reduced' content claim regarded trans fat content (n=48). The focus groups allowed the identification of a noticeable influence of nutrition claims on children, who considered the emphasis important but were confused by the meaning and focus of such claims. Conclusion: Highlighted nutrient claims on the packages of ultra-processed foods were common and seemed to influence the children's perception of the products' quality as a whole. The results indicate the need of thoroughly reviewing the legislation on nutrient claims on the packages of ultra-processed foods.