The increasing emphasis on a competency-based learning approach in entrepreneurial-STEM (E-STEM) necessitates competency-based assessment tools to track students' entrepreneurial development and enhance the quality of E-STEM projects. This study aims to create a valid analytical rubric for assessing students' E-STEM competencies. Using a mixed-methods approach involving semi-structured interviews and a questionnaire, 152 undergraduate students participated. The process of developing the rubric involved two main stages. Phase 1 focused on rubric development, where dimensions and criteria were established. In Phase 2, the rubric was implemented for user validation, including assessment experts, faculty, and students. The research provides a valuable tool for E-STEM teachers to align assessment practices with learning outcomes. Results indicate the effectiveness of the developed E-STEM rubric in offering constructive feedback on learners' competencies and performance. Additionally, the rubric establishes a more visible learning context, enabling students to self-regulate and explicitly assess their entrepreneurial competencies and projects.