Nutrition plays a pivotal role in brain development throughout life. Undernutrition has remained a major problem in Nigeria while overweight and obesity rates are fast approaching that of the developed world. Among the many consequences of malnutrition is its long-term negative effect on intellectual ability and school performance. Good education has been linked to better jobs, higher income, and higher socioeconomic status; while poor school performance with its attendant risk of school dropout results in future income reductions and thereby perpetuates the inter-generational cycle of poverty. The objectives of this study were: To determine the nutritional status of primary school children in Enugu-East LGA, Enugu state; To determine the Intelligence Quotient (IQ) and academic performance of primary school children in Enugu-East LGA; To compare the Intelligence Quotient and academic performance of well-nourished and malnourished primary school children in Enugu-East LGA; To determine the associations of socio-demographic variables (age, gender, socioeconomic status, family size and school type) with the intelligence quotient and academic performance of primary school children in Enugu-East LGA and; To correlate the intelligence quotient and academic performance of primary school children in Enugu-East LGA. This was a cross-sectional observational study conducted among primary school pupils aged 6 to 12 years in Enugu-east LGA. Ethical approval was obtained from the Health Research and Ethics Committee (HREC) of the University of Nigeria Teaching Hospital, Ituku-Ozalla. Approval was also sought from the Enugu State Universal Basic Education Board (ENSUBEB). Children who met the inclusion criteria were recruited from public and private primary schools in the LGA using a proportionate multistage sampling technique. Weight and height were measured using standard protocols and interpreted as normal or abnormal using the WHO AnthroPlus®. Intelligence Quotient was scored using the Raven’s Standard Progressive Matrices (RSPM) and was grouped into optimal and suboptimal. Academic performance was assessed using the past records of class assessment, and was classified into high, average and low academic performance. A semi-structured questionnaire was used to obtain data such as–age, gender, socioeconomic indices and family size of the study participants. Data were analysed using IBM-SPSS version 20 (Chicago II) and a p value less than 0.05 was regarded as significant. A total of 1,122 children were enrolled in the study between November 2017 and February 2018. The prevalence of stunting, wasting, overweight, and obesity was 2.1%, 3.6%, 6.6% and 4.2%. The proportion of optimal and sub-optimal IQ among the participants was 54% and 46% respectively. High, average and low academic performance were seen in 59%, 35% and 6% of the study participants respectively. Overweight and obesity had a significant positive association with IQ (p=0.006 and p<0.001respectively). Academic performance also had a significant positive association with overweight and obesity (p=0.01 and p<0.001 respectively). Stunting and wasting were not significantly associated with IQ or academic performance. Sociodemographic variables such as socioeconomic status, family size and school type were significant determinants of IQ, and academic performance. IQ and academic performance were positively correlated with each other (r=+0.2, p=<0.001).