Abstract Background To benchmark and quantitatively assess the transparency, specificity and comprehensiveness of nutrition-related commitments, as well as related practices of the largest Belgian food companies. Methods The ‘Business Impact Assessment on Obesity and population-level nutrition’ (BIA-Obesity) was applied to evaluate nutrition-related commitments and practices concerning product formulation, labelling, promotion and accessibility by the biggest Belgian food and non-alcoholic beverage manufacturers (n = 19), supermarkets (n = 5) and quick-service restaurants (n = 7). Publicly available commitments were collected and company representatives given the opportunity to verify and complete the information (2019–2020). Commitments were scored according to the BIA-Obesity. To assess company practices, the following indicators were calculated: median Nutri-Score of product portfolios, the proportion of products not-permitted to be marketed to children (using the World Health Organisation Regional Office for Europe nutrient profile model), the proportion of ultra-processed food products (using the NOVA-classification) and the proportion of products displaying Nutri-Score on the front-of-pack. Promotions in supermarket flyers were analysed over a one-year period and quick-service restaurant density around schools was calculated. Correlations between commitments and performance indicators were calculated applying the Spearman's rank correlation coefficient. Results Eighteen out of 31 companies participated (56%). Overall BIA-Obesity scores for commitments ranged from 2 to 75% (median = 35%) with notable variation across policy domains and food industries. The proportion of portfolios consisting of A and B Nutri-Score products ranged from 0 to 100% (median = 29%). The median proportion of products not-permitted to be marketed to children was 81% (range = 12%-100%) and the median proportion of ultra-processed foods was 75% (range = 2%-100%) across product portfolios. No significant correlations were observed ...