Social responsibility is the commitment of business units and society to appropriate legal, ethical and humanitarian actions to support and improve the welfare of society and business units. The social responsibility of the company has been extensively researched from different perspectives. One of the new research trends is the impact of corporate complexity on corporate social responsibility, which shows that more complex companies need more sophisticated reporting and management practices. The purpose of this study is the relationship between company complexity and social responsibility of companies listed on the Tehran Stock Exchange. The information required for this study is taken from the financial statements of 146 companies in the period 1392-1391. In terms of purpose, the research is part of applied research and the research method is correlational in terms of nature and content, and panel analysis has been used to analyze the hypothesis. The results of testing the research hypotheses showed that there is a positive and significant relationship between firm complexity (firm size criteria and financial leverage) and social responsibility; but there is no significant relationship between firm complexity (a combination of complexity and environmental uncertainty) and social responsibility.