Abstract: The purpose of this research was to investigate the influence of project planning on the sustainability of urban water projects in Ruaka Sub-Location, Kenya. The specific objectives focused on stakeholders’ involvement; objectives clarity; feasibility assessment levels; and risk planning. The study was guided by Systems Theory. The study employed a descriptive research design. The study targeted stakeholders involved in urban water projects in Ruaka Sub-Location, whose total population was 10,069. A sample size of 398 participants was determined using Yamane’s formula n=N/1+Ne2 at a 95% confidence level (e = 0.05), incorporating simple random and purposive sampling techniques. Data was collected using questionnaires, interview guides, and observation checklists, with a pilot study conducted to test validity and reliability using Cronbach’s alpha. Quantitative data was analyzed using descriptive statistics and inferential statistics with the help of SPSS v26, while qualitative data was analyzed using thematic content analysis. The findings from both descriptive and inferential analyses revealed that project planning has a statistically significant and positive influence on sustainability. Project planning was found to significantly enhance sustainability through improved clarity of objectives, stakeholder involvement, resource allocation, and alignment with community needs. Correlation analysis showed a strong positive relationship with sustainability (r = 0.712, p < 0.05), while regression results indicated that project planning was a significant predictor of sustainability (β = 0.318, p < 0.05). The model explained a substantial proportion of variation in sustainability outcomes (R² = 0.659), reinforcing the critical role of planning in enhancing long-term performance of urban water projects. The study concludes that project planning significantly enhances sustainability of urban water projects in Ruaka Sub-Location. The study recommends strengthening capacity building and collaboration among different stakeholders to increase the sustainability of water projects in Ruaka Sub-Locaton. Key words: Project Planning; Project Sustainability; Urban Water Projects; Systems Theory; Stakeholders’ Involvement