Utilization of M&E information is considered one of the key components of a functional M&E system. The paper is about assessing the effect of the utilization of M&E information on the effectiveness of the M&E system in the Zanzibar public sector. The study adopted positivist and deductive research philosophy and a quantitative approach. Data were collected through a questionnaire constructed with five points Likert scale from 168 implementers of the Zanzibar Strategy for Economic Growth and Poverty Reduction III (ZSSGRPIII.  Stratified and simple random sampling was used in sample selection. Both descriptive and inferential statistics were applied to data analysis. The results indicate that utilization of M&E information is a  positive and significant predictor of the effectiveness of the M&E system. The findings underscore the importance of integrating M&E information into policy development, evidence-based decision-making, and budgeting processes. Policymakers and practitioners should prioritize the utilization of M&E findings to ensure more effective and informed decision-making. The study suggests the need for strategic interventions to enhance the utilization of M&E findings and improve the overall effectiveness of M&E systems in the Zanzibar public sector.