The process of vendor selection has emerged as a crucial component for achieving success in the construction sector supply chain on a worldwide scale. This may be accomplished by placing emphasis on key variables pertaining to vendors, including their quality, cost, and capacity to perform work. Therefore, the current study aims to investigate the influence of work quality, work expenses, and work capacity on the process of vendor selection within the construction project supply chain in Iraq. This study examines the moderating influence of vendor reputation on the relationship between quality of work, work costs, capacity of work, and vendor selection within the construction project supply chain in Iraq. The major data for this study is obtained through the use of survey questionnaires sent to the supply chain department within the construction sector in Iraq. The present study examines the relationship between the constructs by utilising the statistical software SPSS-AMOS. The findings of the study indicate a positive correlation between vendor selection in the construction project supply chain in Iraq and the quality of work, costs of work, and capacity of work. The results of the study also revealed that the reputation of the vendor plays a significant moderating role in relation to the quality, pricing, and capacity of work, as well as the selection of vendors within the construction project supply chain in Iraq. The research supports the supply chain department in the vendor selection process, wherein the pertinent authorities assess the quality, costs, and capacity of work, as well as the vendor's reputation in the market.