<p>Municipal solid waste management is a critical challenge globally, with increasing urbanization intensifying the need for effective and sustainable solutions. This study conducts an integrated evaluation of a solid waste separation project in Islamshahr Municipality, Iran, employing empirical data and a mixed-methods approach. The economic viability of the project is assessed using a cost–benefit analysis (CBA), which quantifies fixed and operational costs against revenues from waste sales, transportation savings, and land-use benefits. Simultaneously, confirmatory factor analysis (CFA) identifies the key social, technological, managerial, and infrastructural success factors influencing project performance. Findings reveal that the economic assessment highlighted the need for operational improvements, while technological factors exert the greatest impact on success, followed by infrastructural and social components. This study bridges a notable gap in the literature by combining economic and socio-technical analyses within the Iranian municipal context. The integrated methodology offers both theoretical advancements in project evaluation and practical guidance for policymakers aiming to enhance municipal waste management programs. The study recommends that municipal managers prioritize investment in modern technology and public awareness campaigns to enhance the project's economic viability and success.</p>