The objective of this study was to investigate how project management practices influence the institutional performance of public secondary schools in Kitui County. The specific objective was to determine how quality management practices, stakeholder engagement, risk management, and monitoring and evaluation (M&E) influence the performance of public secondary schools in Kitui County. In this study, Systems Theory and Resource-Based View (RBV) Theory were used, with Systems Theory serving as the anchor theory. Systems Theory emphasizes that schools, as complex organizations, consist of interdependent subsystems—administration, teaching staff, students, and the community—that must function cohesively to achieve the overall performance of the school. RBV Theory emphasizes the internal resources of an organization as critical for achieving competitive advantage and sustainability. The study was conducted using a descriptive research design, with a target population of 374 public secondary schools in Kitui County and a sample size of 332, selected through stratified random sampling. A structured questionnaire was used as the main research instrument, and data were analyzed using descriptive and inferential statistics with the help of SPSS software. The presentation of analyzed data was done using percentages, means, and standard deviations, with results displayed in frequency tables. The study findings showed that project management practices significantly affect the performance of public secondary schools in Kitui County. A positive linear relationship between project management practices (such as quality management, stakeholder engagement, and risk management) and school performance suggests that adopting formal project management frameworks enhances school efficiency, project completion rates, and academic outcomes. The study recommends that school administrators and project managers should adopt formal project management frameworks, emphasizing stakeholder engagement, risk management strategies, and quality assurance practices to improve resource allocation and ensure successful project outcomes in Kitui County.