Innovation intermediaries play a fundamental role in strengthening innovation systems. However, their performance evaluation remains a challenge owing to the complexity of their interactions and long-term impacts. This research aims to develop and apply a monitoring and evaluation model for innovation intermediaries based on the Theory of Change (ToC), seeking to systematize the measurement of the results and impacts of the intermediation activities of the Brazilian Association for Industrial Research and Innovation (Embrapii). The methodology combines qualitative and quantitative approaches, integrating ToC with multi-criteria decision methods in an application of the conceptual model within Embrapii s organizational context. This study proposes a performance monitoring and evaluation model that goes beyond Embrapii s current evaluation system and includes systemic transformation indicators and long-term impact measures. The results demonstrate how ToC integration can enhance the evaluation of innovation intermediaries by mapping causal relationships between activities and impacts, identifying appropriate indicators for different result levels, and capturing systemic changes. This study contributes to both theory and practice by providing a structured approach to evaluate innovation intermediaries performance and offers practical guidelines with managerial and policy implications.