In recent years, a growing number of organisations have outsourced logistics services to logistics services providers (LSPs). To account for greater interconnection between organisations, supply chain relationship is crucial for achieving successful logistics outsourcing. Because organisations need to continuously change their decision-making in outsourcing, relationships among organisations in outsourcing are dynamic. Further, because logistics outsourcing has created more supply chain relationships (SCRs) among suppliers, LSPs, and customers, managers need to use a network perspective to manage multiple relationships in the process of outsourcing. The triadic relationship is recognised as the smallest network structure. As a result, the primary goal of this research is to study dynamics of supply chain relationships in logistics outsourcing from a view of triadic relationship. This relationship is called a logistics triad and consists of a supplier, a logistics service provider (LSP), and their common customer. The present research was carried out in two stages. The first stage collected triadic cases from LSPs. To improve validity and reliability, the second stage used a deductive process to test findings of the first stage by collecting triadic cases from suppliers and customers. Results of the comparison between the two stages provided verified research findings because the two stages exhibited close similarity. The research outcomes led to the identification of factors that influenced the relationship dynamics in logistics triads. Among these factors, the combined effects of purchasing volumes, resource capability, and focal firm can override influences from other factors to determine stability and dynamics of logistics triads. Overall, this research makes several major contributions to the knowledge of supply chain relationships: developing an integrative model of triadic relationship dynamics, identifying control approaches used by organisations to dominate triads, and demonstrating organisations' mediating effects on dyadic relationships within triads.