Supervision refers to a school principal who helps teachers to improve the quality of the teaching and learning process in schools by assisting them in developing professional, personal and social competencies, learning processes and all supporting elements. Teachers must be competent and qualified because their responsibilities in a school have a significant impact on student learning experiences and the overall quality of learning and have a positive impact on student learning outcomes. This research aims to describe the effectiveness of the principal's supervision of teachers, teacher professional competence, student learning outcomes, as well as the relationship between the effectiveness of supervision and increasing teacher professional competence and student learning outcomes in the Gugus Ir Teacher Working Group (KKG). Soekarno with qualitative research methods. Based on the research data, it was found that : (1) The effectiveness of the implementation of supervision is effective, but needs continuous improvement and improvements in certain aspects to achieve optimal results in all schools, (2) Most schools in the Ir teacher working group. Soekarno showed good teacher professional competence, but needed increased consistency in the application of best practices in learning, implementation of more effective supervision to increase teacher professional competence through more structured, consistent, and oriented supervision towards developing teacher professionalism, focused professional development through training and constructive feedback, a variety of learning methods to create a more interesting and effective learning experience for students, (3) The research results show that the majority of schools have good learning outcomes, but need improvement, especially in Mathematics learning, (4) Effectiveness of school principal supervision in KKG Gugus Ir. Soekarno had a positive influence and could significantly contribute to increasing teacher professional competence and student learning outcomes. In this research it can be understood that schools that have more structured and consistent supervision tend to show better teacher professional competence and better student learning outcomes. Good. The importance of implementing supervision that is consistent, structured, and oriented towards developing teacher professionalism to improve the quality of teaching and student learning outcomes. School principals must ensure that supervision is carried out routinely with adequate time allocation, as well as intensive follow-up.