AbstractObjectiveTo investigate the relationship between ultra‐processed food (UPF) consumption and dental caries in adolescents.MethodsData from 996 adolescents aged 12–13 years who participated in an oral health sub‐study of the 2004 Pelotas Birth Cohort in southern Brazil were analysed. The main exposure was daily UPF consumption at age 10–11 years, measured by a food frequency questionnaire containing 24 UPF items defined based on the NOVA system. UPF consumption was calculated in frequency, grams and calories, in general and for six types of food (biscuits, savoury snacks and sugar‐sweetened cereals; ultra‐processed meats and fats; sweets; fast food and instant noodles; soft drinks and artificially flavoured drinks; and sweetened milk and powdered chocolate). The outcome was dental caries, measured according to the decayed, missing and filled indexes (DMFS and dmfs) at age 12–13 years. Poisson regression models were used to analyse the association between UPF consumption and dental caries, adjusting for socioeconomic and demographic variables, dental visits and oral hygiene.ResultsOverall, the daily UPF consumption in frequency, grams and calories was associated with caries. The findings were consistent for UPF consumption for all six food groups. The higher the UPF consumption, the higher the probability of having caries in adolescence. The associations between ultra‐processed meats and fats, and fast food and instant noodles intake with dental caries alert to the cariogenic potential of such UPF foods.ConclusionUltra‐processed food consumption was associated with greater caries burdens in young adolescents. The findings reinforce the need for interventions and public policies to reduce UPF consumption in adolescence.