Purpose: Prior research on interfirm collaborations has demonstrated that trust and contract are two central governance mechanisms that influence a firm’s knowledge sharing decision and the subsequent effect on performance. However, we know little about how effective these mechanisms are in different market conditions and levels of organizational innovativeness. This study aims to advance the literature on interfirm knowledge sharing by exploring these contingencies and by providing an alternative explanation of the contradictory effects of knowledge sharing on firm performance. Design/methodology/approach: The authors collected 156 firms’ relationships with their suppliers in two batches from 300 firms in the 2017 list of Statistics in the Zhejiang province in China. The authors used unstructured interviews and formal questionnaires to collect data from these firms. Findings: Market turbulence served as a boundary condition for the effect of interfirm trust and formal contracts on knowledge sharing. Both interfirm trust and formal contracts, as governance mechanisms, are effective in raising interfirm knowledge sharing only when the firms operate in high turbulent markets. On the contrary, knowledge sharing negatively affected firm performance when firms exhibit low organizational innovativeness. Moreover, a three-way interaction among market turbulence, organizational innovativeness and knowledge sharing revealed that when market turbulence and organizational innovativeness were both low, interfirm knowledge sharing was detrimental to firm performance. Practical implications: Based on the results, this study recommends managers consider external (market turbulence) and internal (organizational innovativeness) when firms decide to share knowledge and benefit from such activities. Originality/value: This study extends prior research on the determinant of knowledge sharing and clarifies the inconsistent findings of knowledge sharing on firm performance. Thus, strategic organizational leaders need to pay attention to when they need to share information with suppliers to best benefit from those collaborations.