Introduction: Food insecurity and mixed patterns of malnutrition coexist in rural Nigeria despite the country's agricultural potential. There is a lack of precise data regarding the relationship between household food security and nutritional status of the mother-child pair in southwestern Nigeria. This study examined household food security and mother-child nutritional status in Irele and Okitipupa Local Government Areas (LGAs) of Ondo State. Methods and Analysis: A descriptive cross-sectional community-based survey was carried out with 358 mother-child pairs (children 6-59 months). The Household Food Insecurity Access Scale (HFIAS) was used to measure household food insecurity. Body Mass Index (BMI) was used to assess mothers' and WHO Anthro Z-scores to assess children's nutritional status. Descriptive statistics and Chi-square tests (p < 0.05) were used to examine the data. Results: 93.3% of households were food insecure. A striking double burden of malnutrition was observed: 58.4% of mothers were overweight or obese, and child malnutrition was widespread, with 39.3% stunting, 29.1% wasting and 42.1% underweight. Breastfeeding duration (p = 0.008) and introduction of complementary feeding (p = 0.032) were significant predictors of child wasting. Interestingly, maternal education and income were not significant predictors of child undernutrition (p > 0.05), suggesting that environmental and behavioral influences take precedence over individual socioeconomic status in these communities Conclusion: The simultaneous presence of severe child undernutrition and maternal overnutrition in rural Ondo State suggests a public health crisis in a state undergoing nutrition transition towards energy-dense, low-nutrient foods. These results suggest that national approaches are inadequate. We need interventions that focus on decentralized, LGA-level policies that integrate food security programs with education on Infant and Young Child Feeding (IYCF). Keywords: Food Security, Malnutrition, Stunting, Wasting, BMI, Infant Feeding Practices, Ondo State, Nigeria