Objective: To evaluate potential associations between the consumption of ultra-processed food (UPF) and sugary drinks and the nutritional status evolution among Uruguayan and Brazilian preschoolers, in an attempt to improve public health policies. Design: Cross-sectional analysis Setting: Population based surveys in two Latin American countries, Uruguay and Brazil. Participants: Preschool children Main outcome measures: Obesity: defined as BMI for age and sex ≥ + 3 z-scores, according to the WHO standards Analysis: Crude and adjusted logistic regressions were performed to estimate odds ratios, and respective 95% Confidence Intervals (95%CI), for the associations of UPF consumption and nutritional status in preschoolers. Results: Nearly 5% of the sample of Uruguayan and Brazilian young children were obese. We observed a relationship between score of UPF consumption and obesity (OR: 1.06 (95% CI, 1.01–1.11). Adjustment for weight at birth resulted in modest attenuation of the relationship and lack of statistical significance. The score of UPF consumption was associated with childhood obesity in children under 48 months, OR:1.09 (95% CI, 1.02–1.16). Conclusions and implications: Higher consumption of UPFs and sugary drinks is associated with obesity in Uruguayan and Brazilian children younger than 4 years