PurposeThis paper aims at clarifying important contingencies for the success of knowledge management systems (KMS). More specifically, a model is developed based on the IS success model, the resource‐based view and the knowledge‐based view to explain both direct and indirect effects of KMS on organizational performance.Design/methodology/approachTo test the proposed model, a survey study was conducted involving over 100 organizations that implemented various functions of KMS. The data were analyzed using structural equation modelling for the simultaneous testing of the measurement and structural models.FindingsThe empirical results provided strong support for the proposed research model. KMS usage was found to have both direct and indirect effects on organizational performance. In particular, organizational agility and innovativeness were confirmed as important mediators of KMS effects.Research limitations/implicationsThe findings of this research highlight the necessity of adopting a contingency theory for studying the effects of KMS on organizational performance and demonstrate the important role of some of these contingencies.Practical implicationsPractically, the empirical results shed light on the significance and relative importance of specific KMS applications. i.e. enterprise portals, supply chain management, customer relationship management, and competitive intelligence.Originality/valueThis research fills an important theoretical gap in KM research and provides valuable insights for practitioners.