Project management office is widely claimed to be a critical success factor responsible for Project success. The objective of this study was to identify those project management office role dimension that have the greatest effect on project success and to investigate whether these dimensions are actually in place on study organization Projects. Thirty four (34) projects was selected as the unit of study. Though the Project Success assessment survey questionnaire and Project Management office role questionnaires, linear regression analysis (N=64) were conducted. The findings of this quantitative study supported the research hypotheses and demonstrated that; a significant, positive relationship does exist between “Monitoring and control of project Performanceâ€, “development of project management methodologies and competencies†and “strategy management†with Project success. In contrast Insignificant and negative relationship exist between “multi-project management†and “organizational learning†with Project success respectively. This study identified a cause-and-effect relationship of Project Management office role dimensions and project success. The findings do imply that project success might be improved by improving project management office role on three significant dimensions.