Malnutrition is a public health issue among school-age children. It has been documented that malnutrition is a significant contributor to childhood morbidity and mortality. It affects the growth and development of children negatively. There are also long-term negative consequences on the health, education, psychological/emotional development, and economic productivity of an individual. Malnutrition predisposes to acute infections and chronic non-communicable diseases in childhood. Factors that have been associated with malnutrition in children include sociodemographic factors and child’s physical activity. The aim of this study was to determine the prevalence and the influence of socio-demographic risk factors (such as gender, socioeconomic status, and family size) for malnutrition among primary school children in Enugu-East LGA of Enugu State. The study also compared the proportions of malnutrition among public and private primary schools. The study was cross-sectional and descriptive. Study participants were selected using a multistage sampling technique over a three month period. A proforma was used to collect information such as age, socio-economic status, family size, and child’s physical activity. The weights and heights of study participants were measured using a weighing scale and a stadiometer respectively. The socio-economic status of each participant was determined using a method proposed by Oyedeji. Using 2007 WHO WAZ, HAZ and BAZ reference for school-age children, the participants were categorized into normal or malnourished (wasted, stunted, underweight, overweight or obese). Five hundred and seventy-two (50.6%) pupils were recruited in the public schools while 558 (49.4%) were recruited in the private schools. The male to female ratio was 1:1.2 and the mean age of the study participants was 8.80 ±1.82 years. Malnutrition was observed among 235 pupils (20.8%). Overall, 49 (4.3%) were wasted, 27 (2.4%) were stunted, 12 (1.1%) were underweight, 96 (8.5%) were overweight and 51 (4.5%) were obese. The prevalence of wasting, stunting, underweight, overweight and obesity were 5.8%, 4.7%, 1.9%, 2.6% and 0.7% respectively in the public schools and 2.9%, 0%, 0.2%, 14.5% and 8.4% respectively in the private schools. Stunting predominantly affected older children while overweight and obesity mostly affected younger children. Overweight and obesity were higher among children from the upper socioeconomic class, mothers with a tertiary level of education, those in private schools and children transported to school in cars. Stunting, wasting and underweight were more among children of mothers with secondary level education and below, in the public schools and children who walk to school and among children from low socio-economic class families. Overweight was prevalent among participants from families with four children and less. Obesity was associated with higher screen time a day. Stunting predominated among higher birth-order children.