This study was conducted to provide a comprehensive understanding of determinants of science teachers' healthy eating intentions and behaviors by combining the health belief model and the theory of planned behavior into one conceptual framework and considering the mediating impact of attitude and intention on behavior. This study was conducted based on cross sectional study design between November 2019 and February 2020. A total of 13 hypotheses were tested and data collected from 563 science teachers in Turkey were analyzed using structural equation modeling. The results of the study showed that the proposed model explained the variance in intention and behavior at a more satisfactory level than existing theories. The results also revealed that all of the hypotheses were supported. In addition, the mediating role of attitude and intention in understanding science teachers' healthy eating behaviors was identified. The study can provide important implications for education stakeholders, curriculum developers and science educators.