Child undernutrition persists in Cambodia despite recent progress. As Cambodia undergoes a shift in dietary consumption that coincides with economic, demographic, and epidemiologic changes, there is risk of ultra-processed foods and sugar-sweetened beverages displacing nutrient-dense foods during the critical period of infant growth in the first 24 months. The aim of this study was to assess the introduction and intake of foods of low nutritional value and sugar-sweetened beverages and their association with undernutrition among children 24 months of age in rural and semi-urban Cambodia. Cross-sectional analyses of a 24-h dietary recall from a sample (n = 377) of 24-month-olds found that the majority of infants had been introduced to packaged salty snacks and sweets by 12 months of age and to sugar-sweetened beverages by 15 months. By 24 months of age, 78% of children had consumed foods of low nutritional value and 57% consumed a sugar-sweetened beverage on the previous day. Multivariate logistic regression analyses demonstrated that infant intake of a flavored sugary drink on the previous day was associated with over two times the odds of both stunting and wasting, and consumption of packaged sweets on the previous day was associated with over two times the odds of wasting, but no association was found with stunting. These findings underscore the need to improve educational and policy interventions to support healthy feeding practices for infants and young children.