Objective: Nutrition knowledge among primary school children in Kenya requires improvement because the coverage of nutrition in syllabi has been on a downward trend since independence. A nine-month nutrition education intervention was conducted to address the gap in knowledge among school children in Machakos District. Methodology and results: A baseline survey was conducted among 350 pupils in classes 5 and 6 in 15 out of 23 schools in the zone. Two experimental and two control schools were selected from a rural and urban set-up to participate in the 9-month intervention. Structured questionnaires, focus group discussions, pre-tests and post-tests were used to collect data. SPSS and Nutri-Survey computer packages were used to analyze data in descriptive and inferential statistics. Nutrition knowledge among pupils improved significantly in experimental rural and urban schools compared to the control schools. Although not statistically significant, underweight, stunting and wasting levels before the intervention reduced from 14.5, 28.9 and 3.9% respectively, to 11.8, 21 and 2.6%, respectively after the intervention. Conclusion and potential application of findings: There was significant improvement in nutrition knowledge and practices in both rural and urban experimental schools. Transfer of nutrition information and skills learnt at school to the community was also noted. Although food shortage may be a leading cause of malnutrition, lack of nutrition education is an equally important factor that should be addressed in tackling malnutrition. Nutrition education could be efficiently provided in the enabling environment provided by schools using affordable and easily available resources such as school gardens. More effort should be made to strengthen nutrition education among school children in developing countries.