Financial sustainability leads to the predictability of future profits. Using signaling theory, companies signal market participants through financial sustainability, which leads to greater information transparency, and it is important to examine the factors affecting it, such as managerial optimism and the level of social responsibility. Managerial optimism is a double-edged sword: if it is accompanied by information transparency and strong corporate governance, it can strengthen the relationship between the level of social responsibility and financial sustainability in the direction of company growth. However, in environments lacking transparency, managers' optimism only leads to unnecessary costs and a decrease in the company's financial resilience to economic fluctuations. Therefore, the purpose of this study is to examine the relationship between the level of social responsibility and financial sustainability with the moderating role of managerial optimism. The statistical population of the study is companies listed on the Tehran Stock Exchange and the sample under study includes 165 companies listed during the years 2010 to 2014. The research method is descriptive and in terms of the relationship between variables is causal-correlation, and in terms of the purpose it is applied and in terms of the event, it is post-event. The regression method and panel data as well as the fixed effects model were used to process and test the hypotheses. The research hypotheses showed that the level of social responsibility has a positive and significant relationship with financial sustainability, and considering the negative coefficient of the moderating variable (managerial optimism and level of social responsibility), it can be concluded that managerial optimism has an inverse and significant effect on the relationship between the level of social responsibility and financial sustainability.