Microcredentials, digital competency-based certifications of skills, have emerged as a flexible, personalized alternative to traditional professional development, especially for school leaders with demanding schedules. This study explored the integration of microcredentials to enhance K-12 school principals’ preparedness for leading STEM initiatives. Employing a convergent mixed methods design, the study collected and analyzed quantitative and qualitative data to examine school leaders’ perceptions of microcredentials and experiences with STEM leadership. Quantitative results indicated school leaders’ moderately positive perceptions regarding available STEM resources, beliefs about the value of STEM education, and their capacity to navigate STEM-related challenges. Qualitative findings revealed that microcredentials supported school leaders in addressing gaps in STEM knowledge, aligning STEM tenets with existing instructional assessment rubrics, and engaging in reflective practices that fostered school-wide collaboration and sustained STEM culture. The findings of this study highlight the potential of microcredentials to serve as a targeted, flexible, and competency-based professional learning model that empowers school principals to initiate and maintain effective STEM programs tailored to their school contexts.