Purpose: The paper aims to examine how trust interacts with factors affecting interorganizational knowledge sharing in green supply chains, where cooperation and competition coexist.Design/methodology/approach: A new research model is developed which comprises nine constructs and 13 research hypotheses, with trust as a mediating construct. The nine constructs are measured by well‐supported measures in the literature. The hypotheses are tested on data collected from 288 major green manufacturing firms in Taiwan, using structural equation modeling.Findings: The paper finds that trust is the pivot of the factors influencing interorganizational knowledge sharing. The more a factor contributes to trust positively (such as participation and communication) or negatively (such as opportunistic behavior), the more the factor contributes to knowledge sharing correspondingly. The factors with no significant influence on trust (such as shared values and learning capacity) have no or less influence on knowledge sharing.Research limitations/implications: The empirical study is conducted on green supply chains, with data collected from Taiwan's green manufacturing firms. With the research model developed, cross‐industrial studies on various forms of supply chains can be conducted to investigate whether differences between supply chains exist about the role that trust plays in interorganizational knowledge sharing.Practical implications: The findings of the paper provide useful insights into how supply chain members should reinforce their collaborative behaviors and activities that would enhance the trust‐based relationships, in order to achieve the competitive advantage of knowledge sharing for the supply chain as a whole.Originality/value: The new research model developed allows the relationships between trust and other influencing factors on interorganizational knowledge sharing to be explored. The model reflects the coexistence of the cooperation and competition relationships between supply chain members, which is not dealt with in previous studies.