<p>Sustainability integration has become a strategic priority in higher education, but its influence on students’ learning experience and perceived educational quality remains insufficiently understood, particularly in emerging higher education systems. Drawing on the whole-institution perspective on sustainability, this study examines how student-perceived sustainable development policy integration (SDPI) shapes perceived educational quality (PEQ) in Vietnamese higher education. Specifically, the study tests a moderated mediation model in which student engagement (SE) mediates the relationship between SDPI and PEQ, while internal quality assurance orientation (IQAO) moderates the effect of SDPI on SE and the corresponding indirect effect on PEQ. Survey data were collected from 482 returned questionnaires, of which 378 valid responses were retained for analysis. Using partial least squares structural equation modelling (PLS-SEM), the results show that SDPI positively influences both SE and PEQ, and that SE positively affects PEQ. The findings further indicate that SE partially mediates the relationship between SDPI and PEQ. In addition, IQAO positively moderates the SDPI–SE relationship and strengthens the indirect effect of SDPI on PEQ through SE. These findings suggest that sustainability integration operates not only as an institutional policy commitment but also as a student-experienced quality signal. Its educational value is stronger when supported by internal quality assurance systems that translate sustainability commitments into coherent and engaging academic practices. The study contributes to sustainability-in-higher-education research by explaining how and under what institutional conditions sustainability integration becomes meaningful for students’ engagement and quality perceptions in the Vietnamese context.</p>