Robotics, an emerging tool in STEM education, promises a multitude of educational benefits, ranging from hands-on learning experiences to fostering critical thinking and collaborative skills. However, the integration of robotics in classrooms is primarily contingent upon science teachers' inclination and willingness to adopt this technology. To bridge this gap, this research aimed to explore the adoption of robotics within STEM education by science teachers, by merging the Theory of Planned Behavior, Technology Acceptance Model, and Self-Determination Theory into a unified conceptual framework. Our hypothesis-driven approach tested using data from 605 science teachers across various regions in Turkey. The results indicate a significant positive correlation between science teachers' perceptions of the usefulness and ease of use of robotics and their intent to adopt it in their classrooms. Moreover, intrinsic motivational factors such as perceived autonomy and relatedness played a pivotal role in influencing teachers' behavioral intention towards robotics. The findings revealed that, compared to existing theories, our unified model offers a heightened understanding of the determinants influencing teachers' intentions to use robotics in STEM education. Ultimately, our research not only paves the way for a theoretically enriched understanding of technology adoption in STEM but also presents actionable insights for educators, curriculum designers, and policymakers aiming to capitalize on the myriad opportunities offered by robotics in contemporary education.