Cost approaches to management are necessary for a construction project to operate more efficiently. This study looks at the intricate relationships that exist between cost-control strategies and the success of initiatives to develop the county of Marigat's educational infrastructure. This research attempts to determine the critical connections between cost management strategies and construction project results in light of the challenges associated with successfully completing projects within budgetary limits. The Marigat Sub County Ministry of Education Office reports that 23 out of 32 school construction projects—or 71% of the total are either stopped or falling short of expectations. Therefore, the problem addressed in this study is the significant of cost management practices employed in school construction projects and their influence on construction project performance within Marigat Sub County. The study's overall goal was to examine how cost management practices affect the performance of ministry of education-funded school construction projects in Marigat Sub County. Its specific goals are to evaluate the impact of project resource planning, project cost estimation, and project schedule planning on these construction projects, as well as the impact of each on the ministry of education-funded school construction projects in Marigat Sub County. The findings of the study contributed to existing research by giving insight and evidence-based knowledge regarding cost management practices on school construction projects and how this involvement influences the successful completion and performance school projects. The scope of this research was focused on 132 school projects funded by the Ministry of Education in Marigat Sub County, Baringo. The research adopted a descriptive survey design. The 132 educational programmes in Marigat Sub County that are financed by the ministry of education was the target population. The Yamane formula was used to determine the sample size of the respondents given the total population and the desired level of confidence to get 99 school projects, then a random sampling technique was used to select those 99 school projects from the target population. The study used a questionnaire as data collection tool that was administered to project managers who are school principals. Analysis of data was both descriptive and inferential statistics. The mean score of key performance indicators of project resource planning, cost estimation, cost budgeting, and cost control were above 3.5 out of a maximum of 5 respectively indicating that there was involvement of cost management practices in public school construction projects. The regression model predicts that project resource planning, project cost budgeting and project cost control leads to a .154, .208 and .225 increase in project performance respectfully while project cost estimation leads to .116 decrease. In conclusion, the researcher found that cost management practices influence the performance of ministry of education-funded school construction projects in Marigat Sub County. It is therefore recommended that managers of public-school projects to ensure there is proper cost management practices in undertaking of school construction projects.