BACKGROUND AND OBJECTIVES: Sustainable development is a process that envisions a desirable future for human societies in which living conditions and resource use meet human needs without compromising the integrity, beauty, and stability of vital systems. Knowledge-based companies today are among those companies that act as factories for converting knowledge into goods and services. In this regard, organizational social responsibility can be the basis for the sustainable development of companies and organizations. Therefore, this research aims are to examine the role of the organization’s social responsibility for sustainable development in terms of mediating the participation of employees of knowledge-based companies.                                                                                                                                METHODS: This research is applied in terms of purpose, descriptive survey and correlation in terms of method. Field and library methods, literature reviews, and standard questionnaires were used to collect information. The statistical population consisted of 578 senior and middle managers of knowledge-based companies in the Science and Technology Park of Sharif University of Technology, Tehran- Iran, and 231 people were sampled using Cochran's formula method and stratified random sampling. A standard questionnaire was also used to collect information. The validity of the questionnaire was checked and confirmed using convergent and divergent validity and confirmatory factor analysis and its reliability using Cronbach's alpha coefficient, joint and combined reliability. Finally, the collected data was analyzed using SPSS and smartPLS software’s.FINDINGS: Based on the results of the Kolmogorov-Smirnov test, the significance of this test was calculated for all indicators less than 0.05 and 0.000, and due to the lack of normal distribution of the data, the smart PLS software was used. The overall fitting criterion was calculated to be 0.551, which means that the model fits well. When testing the main hypothesis, a coefficient of 0.408 was calculated, showing that employee participation explains 40% of the impact of social responsibility on sustainable development. The path coefficient of the sub-hypotheses for these relationships is above 0.5 and the significance is above 1.96. It can be said that the sub-hypotheses of the research are confirmed.CONCLUSION: According to the indicators obtained, the organization’s social responsibility positively and significantly impacts sustainable development and employee participation. The positive role of employee participation in sustainable development was also confirmed. Finally, the results showed that employee participation can mediate the impact of social responsibility on sustainable development.