Knowledge sharing is vital for any organization, and it has an essential impact on developing skills, increasing value, and maintaining a competitive advantage in the organization. In the knowledge management (KM) literature, perceived organizational support and organizational trust have been pointed out as primary factors for knowledge sharing. The present study investigated the role of perceived organizational support in promoting nurses' knowledge sharing, considering organizational trust as a mediator. The cross-sectional study design was applied to examine the hypothesized relationships. Data were collected using three questionnaires from three hundred thirty nurses working in five public hospitals in Shiraz city. The Partial Least Squares Structural Equation Modeling (PLS-SEM) approach was used to analyze data. The results revealed a significant and positive association between perceived organizational support, organizational trust, and knowledge sharing. The findings also demonstrated that organizational trust plays a mediating role between perceived organizational support and knowledge sharing.