BackgroundNutrition, associated with nutritional status, influences the growth of children. This study aimed to identify the association between maternal diet quality and the diet and body composition of their children.MethodsThis is a prospective longitudinal study with mother-child pairs. To assess diet quality, nutritional status, and socioeconomic data, two interviews in the children’s first and third months of life (2011–2016) and one interview when children were of preschool age (2017–2019) were performed. Diet quality was assessed based on daily food consumption and frequency, considering: 1) food groups, based on the Brazilian food pyramid; 2) level of processing, according to the NOVA classification (unprocessed and/or minimally processed foods, processed foods and ultra-processed foods). One-way ANOVA with Tukey post hoc and Kruskal-Wallis with Dunn’s post hoc tests were used to evaluate the influence of factors on children’s diet quality. Pearson and Spearman’s correlations were used to evaluate the relationship between maternal and children’s diet quality, maternal schooling level, and child age. Along with the nutritional assessment of children, multiple linear regression models assessed the impact of covariables on maternal and children’s diet quality.ResultsEighty-three mother-child pairs participated in this study. The more frequent the maternal consumption of unprocessed and/or minimally processed foods, the higher the consumption of these foods by children (r = +0.30; p = 0.006) and the lower their subscapular skinfold (SSF) thickness (p = 0.011; β = -0.278). On the other hand, the higher the maternal consumption of ultra-processed foods, the higher the children’s tricipital skinfold (TSF) thickness (p = 0.010; β = +0.274) and SSF (p = 0.043; β = +0.222).ConclusionMaternal diet quality was associated with the diet and body composition of children.