Teacher professionalism determines the quality of education output. Hence, this study aims to explore the effect of good corporate governance (GCG) and knowledge management (KM) on the teacher's professional performance in Indonesia mediating by affective commitment. A questionnaire collected the research data through the survey method. The research participants are 375 teachers spreading across three provinces (Jakarta, Banten, West Java) determined by accidental sampling. Data analysis uses path analysis supported by descriptive statistics. The results show that GCG and KM have a significant effect on the teacher's professional performance, either directly or indirectly, mediating by affective commitment. The affective commitment has a direct effect more adequate on the teacher's professional performance than GCG and KM, KM has a direct effect more adequate on teacher's affective commitment than GCG, and KM has an indirect effect more appropriate on the teacher's professional performance mediated by affective commitment than GCG. Therefore, a fit research model about the effect of GCG and KM on the teacher's professional performance mediated by affective commitment was found based on data from teachers in Indonesia. This model can be adopted as a reference or discursus by researchers and education practitioners in developing teacher professional performance models in the future and various contexts, fields, and educational organizations.