Organisations providing essential services are crucial for job creation and significantly contribute to economic growth in developing countries like Kenya. However, many of these organisations face challenges in meeting customer needs and maintaining employee performance standards. This study examined the effect of career planning on employee performance at Murang’a Water and Sanitation Company Limited (MUWASCO) in Kenya. Using a descriptive research survey design, the study employed a census sampling technique, resulting in a sample of 150 respondents. Data was collected through self-administered questionnaires. Data analysis was conducted with the aid of SPSS as a research tool and included both descriptive and inferential statistics. A one-way analysis of variance (ANOVA) was applied to assess the significant differences in the effect of career planning on employee performance. The findings established that career planning has a significant impact on employee performance, with regression analysis showing that changes in career planning directly affect performance outcomes. The study concluded that there is a positive and statistically significant relationship between career planning and employee performance. Based on these findings, it is recommended that MUWASCO should allocate more resources to skills development, provide incentives to encourage employee participation in development programs, establish a clear career guidance policy, and organise regular seminars, mentorship programs, and conferences to further enhance employee performance.