Collaborative commerce system (CCS) is an information technology (IT) application built on the foundation of partners’ relationship, thus its development decision needs to take the collaborative relationship into consideration. This study aims to understand what factors influence the implementation of collaborative commerce (c-commerce) and to explore how the collaborative relationship affects the engaged parties’ CCS decision. Four cases were studied to answer the research questions. The results reveal that the project will be successfully implemented when the degree that internal processes affected by the CCS are acceptable to the engaged parties and their capacities for information technology infrastructure can support the CCS. Moreover, partners with closer relationships tend to use a more complex CCS. This also means more resources, such as time and cost, required to develop the CCS. Finally, the CCS may also facilitate the development of good relationship quality. The research contributes to revealing how the CCS decision is related to collaborative relationship, which provides a new perspective for further research in c-commerce. The findings can also be applied in practice for serving as a reference in making the CCS decision that can promote the quality of collaborative relationship and help the successful implementation of the c-commerce project.