‘Health and nutrition’ is one among the five areas covered by the Aspirational District Programme in India, which aims to achieve the Sustainable Development Goals (SDGs). The reduction of undernutrition in under-five children has remained a major focus of the SDGs, especially at the ages of 6–23 months as this affects child development. This study used National Family Health Survey 2015–16 data to examine appropriate feeding practices and their associations with undernutrition among children aged 6–23 months in the 124 aspirational districts of India. Multinomial logistic regression analysis was used to analyse the association between feeding practices and undernutrition, adjusting for covariates. A total of 13,851 children aged 6–23 months were included in the analysis. Child nutritional outcomes, and children receiving the recommended minimum dietary diversity (MDD), minimum meal frequency (MMF) and minimum acceptable diet (MAD), were poorer in the aspirational compared with non-aspirational districts. However, the proportions of children who continued to breastfed, i.e. currently breastfeeding and the proportion of children who were receiving appropriate breastfeeding, i.e. receiving complementary feeding, in addition to breast milk, were higher in the aspirational districts. Appropriate breastfeeding and MDD were found to be associated negatively with undernutrition. While the continuation of breastfeeding increased the odds of children being undernourished, appropriate breastfeeding lowered the odds. The significant predictors of undernourishment among the study children were the child being male, of higher birth order, older and of smaller than average birth size; mother’s lower educational level, mother’s lower BMI of mothers and being a teenage mother; and poor household drinking water, sanitation facilities and lower economic status. This study suggests that educating mothers, especially illiterate and poor mothers, about appropriate breastfeeding and dietary diversity could help prevent and reduce child undernutrition in the aspirational districts of India.