Background: Child malnutrition is one of the measures of health status that the World Health Organization (WHO) recommends for equity in health. According to WHO, 60% of all deaths occurring among children aged less than 5 years in developing countries is attributed to malnutrition. To improve on this condition, it is necessary to determine the determinants of malnutrition. Methods: This was a descriptive cross-sectional study conducted at Machakos Level five hospital from mothers attending MCH/FP clinic. Using random sampling, seventy (70) mothers and their children 6 months to 60 months participated in the study. Using a questionnaire, socio demographic characteristics and weaning practices were taken as well as children anthropometric measurements (mid-upper arm circumference – MUAC). SPSS version 16.0 statistical software was used for analysis. Results: Out of the seventy children who were involved in the study, 19 (27.1%) were males while 51 (72.9%) were females. The age ranged was 8 months to 60 months. The results obtained showed that socioeconomic factor, poor nutrition and mothers’ knowledge and feeding practices led to increase in the prevalence of malnutrition. Mid Upper Arm Circumference (MUAC) was measured using non-stretchable tape on left mid upper arm with the outcome showing that 17 (24.3%) had severe malnutrition, 8(11.4%) had moderate malnutrition, 31 (44.3%) had mild malnutrition while 14 (20%) were well nourished as classified according to World Health Organization. In addition, 41 (58.6%) of children were underweight and that only 22 (31.6%) practices exclusive breastfeeding for the first six months. There was a significant association between the age of the mother and child gender, weaning age of the child and baby feeding frequency per day (p˂0.05). Discussion: The findings from this study suggest that socio-economic factors such as lack of knowledge on the cause of malnutrition child feeding weaning age and the frequency of daily baby feeding practices are predictors of malnutrition in less than five. These findings are of practical importance because they can form part of preventing programs for community. Conclusion: Feeding practices (pre-lacteal feeding and complementary feeding practice) were related to malnutrition thus, nutritional intervention program in Machakos County in Kenya should focus on these factors in order to improve child feeding.