Most building construction projects in Ethiopia have a problem to complete with the scheduled time frame, estimated budget, expected quality, etc. Those problems are a combination of technical and human skill factors. Thus, the purpose of this research is to assess the competence of construction project managers and its impacts on project success in the case of Bahir Dar city public building construction projects. The study covers only Grade -1 general and building contractors. Purposive sampling technique was used to select the research population. Both primary and secondary data are collected to achieve the intended research objectives. Questionnaires and semi-structured interviews were employed as instruments of data collection. The respondents were project managers, site engineers, office engineers and site supervisors. Questionnaires were distributed to project sites for 57 participants. Furthermore, 9 semi-structured interviews were conducted with project managers and project coordinators. The data were analyzed using SPSS 20 and MSExcel 16. The findings of this study revealed that: in hard competence, like time management, financial management, cost management and quality management, project managers have high level of competence. Whereas, in integration management, scope management, procurement management, PM software competence, risk management, safety management and environmental management, project managers have a medium level of competence. The findings of this study also revealed that: in soft competence, like communication, organizing, team working, positive work attitude and conflict management, the project managers have high level of competence. While, in leadership, flexibility & alertness, problem-solving, human resource management and creativity & innovation, project managers have a medium level of competence. The top five project success criteria that were impacted by the competence of project managers were found to be project cost, project time, technical specifications and functional requirements, clients’ satisfaction and stakeholders’ relationship. The study results also shows that project managers’ competencies have high level of impact on project success. This research also has a proposed conceptual framework for project managers’ competencies development.