This study was conducted to assess effectiveness and challenges of educational supervision in improving instructional activities in selected government primary schools of Bole sub-city in Addis Ababa City Administration. A descriptive survey design was employed and purposive sampling and simple random sampling techniques were employed to select 7 government primary schools with 7 cluster supervisors, 10 school principals and 409 teachers who were included in this study. Questionnaire was the main quantitative data gathering tool in which 389 teachers filled the questionnaires. An interview was also conducted for 10 school principals and 7 cluster supervisors. The quantitative data was analyzed by using mean scores and F test by using SPSS v.23.o. The main findings come out from this study were: instructional supervisors prepare clear and well-organized plan for instructional supervision but with the deficiency of implementing properly and efficiently; the actual supervisory practices were not aligned with the expected standards of supervision; the teachers' attitude towards instructional supervisory activities were negative and instructional supervision activities were encountered with several challenges that hinder its effectiveness. And finally, some conclusions were drawn such as supervision activities were not implemented according to their plan and the supervision practice encountered with many challenges; and recommendations were forwarded as instructional supervisors should give due attention for each and every instructional supervision activities, exert their effort to change the teachers' negative perception towards instructional supervision activities through convincing them and overcome the encountered challenges in collaboration with the concerned bodies of education sector at each level of hierarchy and with other stakeholders of the schools.