OBJECTIVES: To evaluate the prevalence of advertisements for ultra-processed products outside food outlets in Montevideo (Uruguay) and explore the patterns of these advertisements across areas with different socio-economic statuses (SES). DESIGN: Cross-sectional field survey of advertisements of ultra-processed products outside food outlets. The percentage of outlets featuring any type of advertisement of ultra-processed products on the exterior part of the outlets was calculated, at the aggregate level and separately by type of outlet and type of product. Comparisons were made considering the SES of the tract where outlets were located. SETTING: 106 census tracts in Montevideo, differing in geographical location and SES. PARTICIPANTS: Outlets selling foods and beverages, located within the selected census tracts. RESULTS: 30·7 % of the 1217 food outlets identified in the field survey featured some type of exterior advertisement of ultra-processed products. Sweetened beverages (specifically soda) were the most frequently advertised ultra-processed product category, followed by ice cream. After adjusting for the type of outlet, medium SES tracts exhibited the highest prevalence of ultra-processed product advertisements outside food outlets (36·0 %). Differences in the prevalence of advertisements of specific categories with SES were also found, which may reflect variations in the types and characteristics of food outlets. CONCLUSIONS: Results from this work suggest the frequent presence of exterior advertisements of ultra-processed products and highlight the need to develop effective policies to reduce their use as part of a comprehensive set of strategies to discourage the consumption of ultra-processed products.