This study aims to conduct a comparative analysis of the determinants influencing the self-efficacy of teachers in South Korea and Finland from a comparative education perspective. To achieve this, we employed Random Forest and Least Squares Dummy Variable (LSDV) regression analysis to comprehensively explore various variables that could impact teachers’ self-efficacy. Additionally, we sought to examine whether these variables were common factors across both countries or unique to each nation's context, in order to derive policy implications. The comparative analysis of the factors influencing teachers’ self-efficacy in South Korea and Finland revealed that factors such as instructional activities, clarity of explanations, and satisfaction with instructional autonomy were common factors enhancing teacher self-efficacy. Furthermore, we identified unique factors influencing teacher self-efficacy in each country. In the case of South Korea, team innovativeness within schools was a distinctive factor, while in Finland, the self-efficacy related to multicultural teaching and overall job satisfaction were specific influences. Based on these findings, this study suggests that within the South Korean context, policies aimed at promoting teacher expertise in instructional activities, instructional autonomy, and school-based team innovation are essential, and emphasizes the need to enhance the reciprocal relationship between these influential factors in teacher professional development policies.