Teacher self-efficacy is a critical component of school life quality, leading scholars to explore the mechanisms behind it. Most studies have focused on this factor's mediation and moderation functions, with some indicating a strong link between teachers' academic optimism and self-efficacy. However, the roles of teachers' professional development and subjective well-being in this connection require further investigation. Our study takes an exclusive approach by positioning teacher self-efficacy as the outcome variable and examining how teacher academic optimism is predicted through teacher professional development and subjective well-being. Data were collected from 405 teachers working in K-12 schools in Türkiye and analyzed using a cross-sectional design. Using the bootstrapping technique, structural equation modeling results confirm the relationship between teacher academic optimism and self-efficacy. The findings reveal that teachers' professional development and subjective well-being mediate the relationship between teacher academic optimism and self-efficacy. In this regard, our paper makes original contributions to the education literature by highlighting the importance of teachers' self-efficacy. Importantly, our findings carry practical implications for practitioners and policymakers, and we offer specific suggestions based on the results to help them make informed decisions.