Higher Education Institutions (HEIs) play crucial role as centers of learning in promoting Education for Sustainable Development (ESD) with the rising enrolment in tertiary education. Beyond cultivating valuable knowledge for future generations, HEIs are also expected to manage campus operations in a more sustainable manner to achieve world-class status while maintaining competitiveness in international rankings. An Integrated Management System (IMS) are often used to achieve sustainable performance. It refers to the implementation of at least two different management systems through holistic approach. In addition to lowering costs, improving resource efficiency, and minimizing conflicts between systems, integration also helps organizations reduce potential risks. Despite these advantages, acceptance of IMS in the education sector remains significantly lower compared to other industries worldwide. Empirical studies on IMS acceptance within the context of HEIs are also limited. Furthermore, IMS is often viewed primarily as a business practice, with minimal theoretical contribution. The proposed conceptual model seeks to address these gaps by examining the external influence of institutional isomorphism on IMS acceptance. Theoretically, this study contributes to the body of IMS literature by extending the theory of Institutional Isomorphism to incorporate organizational experience, unlike previous studies that focused solely on external pressures. From a practical standpoint, the study enables HEIs to understand the determinants of IMS acceptance and emphasizes the standing of a systematic and integrated approach in accelerating the Sustainable Development Goals (SDGs) attainment at the national level.