In the digital era, information technology support services serve as the backbone of organizational processes and play a vital role in ensuring the continuity of operations within public institutions. The Foundation of Martyrs and Veterans Affairs, as an organization dedicated to serving the veteran community, has become increasingly dependent on stable and secure information systems. However, selecting an appropriate contractor for maintaining these systems represents a complex challenge due to the diversity of evaluation criteria, budgetary constraints, and governmental compliance requirements. Traditional tender evaluation methods are often one-dimensional and incapable of effectively resolving conflicts among cost, quality, risk, and legal compliance considerations. Multi-Criteria Decision-Making (MCDM) approaches provide an innovative solution to this issue; nevertheless, their application within the Iranian public sector, particularly in the domain of IT support services, remains limited. The present study aims to design a decision-making framework based on the Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE) method for selecting IT maintenance service contractors in public organizations. Initially, 42 sub-criteria were identified across six principal dimensions. Subsequently, through three rounds of the Delphi method involving 15 experts, these were reduced to 20 final criteria. A hybrid weighting approach combining expert judgment and Shannon entropy identified service quality, technology, and economic factors as the highest-priority dimensions. Five contractors were then ranked using the PROMETHEE II method. The robustness of the proposed model was confirmed through sensitivity analysis, Geometrical Analysis for Interactive Aid (GAIA) analysis, and complete correlation with the SAW method. The proposed framework addresses the lack of indigenous methodologies in the governmental sector and provides a practical tool for risk reduction and cost optimization. By integrating the Delphi method, hybrid weighting techniques, and multi-layer validation procedures, the model offers an operational instrument for governmental decision-makers to achieve transparent, sustainable, and optimal contractor selection. The findings facilitate targeted contractor selection and support sustainable policy-making.