The last decade witnesses a heave use of social media-based information systems in different fields of business such as logistics, procurement, and supply chain management. Managing these types of information systems, could help companies to outsource their supply chain functions in a global scale and enhance their competitive advantages. However, the digital performance of these activities inherent risks of inappropriate supplier selection, lack of trust, bounded rationality and uncertainty about the supply conditions (e.g., pricing, shipping and timing). To address such challenges, this research explains how companies use e-reputation systems and social media to select their global trusted suppliers. Based on two-case evidence from British Diamond and Egyptian Automotive companies, the researchers conducted 20 interviews with purchasing and supply chain professionals. Chen & Lin's reputation system model has been adopted to explain the process of selecting and evaluating a trusted supplier and to inform our data analysis. Our findings referred to the lack of experience among diamond professionals on how to use e-reputation systems and their lack of understanding to the role of social media-based ratings or referrals during the stages of selection suppliers' discovery and approval. Though, automotive professionals find e-reputation system a strong tool to build goodwill, tacit credibility, competence and predictable trust. Ironically, both cases confirm that supply chain professional use these systems to re-evaluate and reselect their existing suppliers than to extend new supply networks.