Dental caries is a chronic oral condition that disproportionately affects low-income women. The aim of this research was to investigate relationships between dental nutrition knowledge, socioecological factors, and prevalence of dental caries in low-income women. This quantitative cross-sectional study involved 220 women who were recruited from Central Texas. Participants completed demographics, the Dental Nutrition Knowledge Competency Scale, United States Adult Food Security Survey Module, and the Multidimensional Home Environment Scale. Two dentists measured dental caries via the Decayed, Missing, Filled Teeth Index. Regression models were conducted to test the effects of dental nutrition knowledge and Multidimensional Home Environment Scale factors on dental caries. Finally, mediation analysis explored relationships between dental nutrition knowledge and dental caries, adjusting for Multidimensional Home Environment Scale scores. Results showed that dental nutrition knowledge and Multidimensional Home Environment Scale score were significantly associated with dental caries. Subscales of self-efficacy for eating healthy, oral hygiene practices, emotional eating, availability of unhealthy foods at home, and social support were related to dental caries. The relationship between dental nutrition knowledge and caries was mediated by Multidimensional Home Environment Scale scores. This research emphasizes the role of dental nutrition knowledge and socio-ecological factors on prevalence of dental caries. Public health interventions to reduce dental caries should involve strategies that increase dental nutrition knowledge and encourage behavior change in low-income populations.