Nairobi slums face significant challenges in nutrition due to poverty, limited access to healthy food sources, and inadequate healthcare infrastructure. A longitudinal study using pre- and post-intervention surveys, focus group discussions, and anthropometric measurements to assess changes in nutritional status and food intake patterns. During the four-year intervention period, there was a statistically significant increase in fruit and vegetable consumption among schoolchildren by 20%, leading to modest improvements in body mass index (BMI) scores. School-based nutrition interventions can be effective in improving dietary habits and health outcomes of urban children in Nairobi slums, but further tailored programmes are needed. Integrate community engagement into future interventions, provide nutritional education materials for parents, and monitor long-term sustainability of the initiatives.