Abstract <p>Rapid urban expansion has increased municipal solid waste generation and demand for construction materials. Repurposing municipal solid waste incineration (MSWI) fly ash into construction materials (FA-to-CM) offers a dual-purpose solution. This paper presents a novel decision support framework to identify sustainable FA-to-CM pathways through environmental, economic, and technical evaluations. The framework incorporates an innovative weighting method and an enhanced vector-based ranking approach, leveraging objective data characteristics for multi-criteria assessment. For the weighting method, fuzzy cognitive map (FCM) is enhanced by integrating data correlations and variations, shifting from subjective judgments to data-driven reasoning to infer complex interrelationships and assign weights to the criteria. For the ranking approach, a dual-matrix best–worst projection method is proposed to identify optimal solutions, balancing performances across multiple dimensions. This study pioneers a comprehensive evaluation of FA-to-CM alternatives, offering mathematical contributions to the objective weighting of interrelated criteria and ranking alternatives from a balanced and holistic perspective. A case study comparing five processes based on nine criteria reveals that environmental considerations outweigh economic and technical criteria. The preferred pathways include transforming MSWI fly ash into ceramics and recovering metals for construction use.</p> Graphical abstract <p></p>