Water resources sustainability in water-stressed regions is simultaneously influenced by hydrological, environmental, socio-economic, and institutional factors; therefore, assessments based solely on technical indicators cannot fully capture the complexity of integrated water resources management (IWRM). This study develops an integrated and multidimensional framework for assessing water resources sustainability and IWRM performance in Alborz Province, Iran. The framework incorporates 22 indicators across four dimensions, namely hydrological sustainability, environmental sustainability, socio-economic sustainability, and water governance. The selected indicators were assessed using data obtained from relevant organizations and institutions. Following normalization, the indicators were weighted using the Analytic Hierarchy Process (AHP) and integrated within a multi-criteria assessment framework. The consistency ratio of expert judgments was below 0.10, indicating an acceptable level of consistency in the derived weights. The results indicate that water resources sustainability in Alborz Province is not governed solely by physical water constraints; rather, governance-related challenges, including institutional fragmentation, weak inter-organizational coordination, limited stakeholder participation, and deficiencies in transparency and accountability, represent important factors affecting IWRM performance. By simultaneously integrating hydrological, environmental, socio-economic, and governance dimensions, the proposed framework provides a quantitative and structured basis for identifying sustainability constraints and supporting decision-making in water-stressed regions. The framework can therefore contribute to bridging the gap between conventional water-resources assessment and institutional and governance-oriented evaluation of IWRM.