Social capital includes the characteristics of social life, norms, and trust that enable participants to collaborate with each other and more effectively and efficiently achieve their common goals. The purpose of this study was to investigate the effect of social capital on employee creativity with regard to the mediating role of knowledge management. The research is of an applied type and descriptive-correlational method. The statistical population of the study included 233 employees of Imam Khomeini University of Marine Sciences, Nowshahr, of which 146 were considered as the sample size. Three standard questionnaires of social capital by Cheng and Chang (2011), knowledge management by Darroch (2003), and creativity by Torrance (1959) were used to collect data. Data analysis was performed using AMOS-V20 software. The findings showed that social capital has a positive effect on creativity and knowledge management of employees of Imam Khomeini University of Marine Sciences, Nowshahr, and knowledge management also has a positive effect on creativity; Also, knowledge management plays a mediating role in the effect of social capital on employee creativity at Imam Khomeini University of Marine Sciences, Nowshahr. According to the research findings, it can be said that by increasing trust and interpersonal relationships, as well as sharing knowledge at Imam Khomeini University of Marine Sciences, Nowshahr, employee creativity can be increased. Finally, a structural model of the effect of social capital on employee creativity with the mediating role of knowledge management is presented.