Religious tourism, particularly in connection with large-scale events such as the Arbaeen pilgrimage, represents one of the key capacities for economic and cultural development in Ilam Province, Iran. The present study aims to examine investment opportunities in the religious tourism sector of this province with particular emphasis on the Arbaeen event. The research adopts a mixed-methods approach (qualitative–quantitative) and was conducted with the participation of 17 experts from the Cultural Heritage Organization, scholars, and professionals active in the fields of tourism and investment, who were selected through purposive sampling. In the first stage, 21 investment opportunities were identified and classified using the Jansen–Verbeke model into three categories: primary, secondary, and supporting elements. In the second stage, evaluation criteria were determined, including feasibility, profitability, year‑round sustainability, accessibility to the supply chain, and market attractiveness. In the third stage, the identified criteria were weighted using the expert panel method. The results indicated that feasibility, profitability, and market attractiveness were the most important criteria, respectively. Finally, in the fourth stage, the identified opportunities were prioritized using the TOPSIS technique. The findings reveal that within the primary elements, establishing vehicle service stations (supply chain services); within the secondary elements, constructing bath and sanitary facilities; and within the supporting elements, establishing temporary field clinics along the pilgrims’ travel routes were identified as the highest-priority investment opportunities in each respective category. In addition to contributing to the theoretical literature, the results of this study provide practical recommendations for investors, policymakers, and planners involved in managing the Arbaeen event in Ilam Province.
