Background: Public trust is a crucial concept in the COVID-19 pandemic, which determines public adherence with preventive rules as a success factor for disease management. This study aimed to develop and validate a tool to measure public trust in COVID-19 control and prevention policies (COV-Trust tool). Methods: This is a psychometric study that was conducted in 2020 (March-August). A primary tool was developed through literature review, in-depth interviews with experts and expert panel meetings. Content and construct validity was evaluated using content validity index (CVI) and content validity ratio (CVR) indexes and exploratory and confirmatory factor analysis, respectively. Cronbach α coefficient was calculated to determine the internal consistency. Results: A 28-item questionnaire with seven factors was developed. Factors included macro policy-making and management of pandemic, pandemic control policies implementing at all levels and their effectiveness, providing protective equipment and medicine for hospitals and public, prevention of negative socio-economic consequences of the pandemic, public participation, informing and public education and public behavior. The questionnaire reliability was calculated to be α = 0.959. Based on the experts’ opinion, tool content validity was estimated to be CVR = 0.73, CVI = 0.89. RMSEA = 0.07 revealed a good model fit as the confirmatory factor analysis results for the tool. Conclusion: COV-Trust tool is a well-fit tool to be used during this pandemic for improving policies effectiveness and could be used in similar situations as it determines the success of public health interventions.