Entrepreneurial STEM, an interdisciplinary approach blending STEM and entrepreneurship education, has become a new trend for cross-subject collaboration that aims to instill an entrepreneurial mindset in students, enabling them to apply their STEM knowledge across various contexts. In this study, we investigate the challenges and corresponding strategies of head science teachers who initiated an entrepreneurial STEM (Science, Technology, Engineering, Mathematics) curriculum in their schools. Grounded in social exchange theory, we explore how head science teachers with entrepreneurial attributes navigated asymmetrical power distribution presented by principals and other subject heads. This collective case study focuses on three schools in Hong Kong that successfully implemented a renowned entrepreneurial STEM curriculum. The findings reveal a common trajectory among head science teachers: initial enthusiastic promotion of the curriculum while meeting resistance; a downscaling and team reform struggles; and a handover and scale-up. This study illuminates the intricate process of balancing power dynamics and stakeholder perceptions through reciprocal negotiation, which were in turn shaped by societal norms.