Background: Social entrepreneurship is increasingly seen as a strategic engine for the Sustainable Development Goals (SDGs) in countries with a majority of Muslims. However, there are few empirical studies that treat Maqāṣid al-Sharī'ah as a measurable construct within entrepreneurial ecosystem models, and there is little data on how entrepreneurial associations like the Indonesian Young Entrepreneurs Association (HIPMI) influence this process. Method: This study used a quantitative, explanatory approach to survey 255 HIPMI members in North Sumatra, Indonesia, using a five-point Likert-scale questionnaire. Partial Least Squares Structural Equation Modeling (PLS-SEM) was used to analyze the data. Results: The measurement model met all validity and reliability criteria (AVE = 0.777–0.902; Cronbach's Alpha and Composite Reliability above 0.90), while the structural model demonstrated strong predictive relevance (Q² = 0.679–0.738), substantial explanatory power (R² = 0.764–0.886), and a good overall fit (SRMR = 0.038). Social Entrepreneurship was one of the twelve hypotheses that received support.Features that have the most beneficial impact on Maqāṣid al-Sharī'ah (β = 0.600). External support had no discernible direct impact on Maqāṣid al-Sharī'ah, while the role of HIPMI had no discernible direct impact on SDG Contribution. However, both relationships gained significance after being mediated by the Social Entrepreneurship Ecosystem. Conclusion: These results corroborate the Islamic Social Entrepreneurial Ecosystem Model (ISEEM), demonstrating that when entrepreneurial capacity, ecosystem development, institutional support, and the internalization of Maqāṣid al-Sharī'ah work together, sustainable development is strengthened.