Abstract: This study examined how project management practices, particularly project planning, influence the performance of NGO-funded health initiatives in Nairobi City County, Kenya. Guided by Goal-Setting and Stakeholder theories, the research adopted a mixed-methods design involving 910 project staff and 10 project managers. Stratified and simple random sampling selected respondents, while key informants were identified purposively. Data were collected using structured and semi-structured questionnaires, validated through a pre-test in Kiambu County, and analyzed using SPSS Version 28 through descriptive statistics and regression analysis. The results indicated that project management practices significantly and positively affect project performance, explaining about 59% of performance variation. Among these practices, project planning had the greatest influence, followed by the utilization of project findings and monitoring systems. Execution and leadership showed minimal impact on performance. The findings highlight that effective planning, robust monitoring, and systematic application of project findings are critical to achieving better health outcomes in NGO-funded initiatives, while mere execution without strategic alignment has limited value. The study recommends that NGOs and policymakers prioritize comprehensive planning frameworks, strengthen monitoring mechanisms, and integrate evidence from past projects to enhance the sustainability, efficiency, and impact of health programs in Nairobi City County. 

Keywords: Project Planning, Performance, NGO-funded, Health Initiatives