Purpose: The cost of capital is a critical factor influencing investment decisions and company financing. Sustainability reporting also enhances the strategic and organizational legitimacy of companies. Therefore, it is expected that sustainability reporting can influence company legitimacy with enhancing trust of companies, their capital costs is reduced. Based on this premise, the objective of this research is to investigate the impact of sustainability reporting on the cost of capital of companies listed on the Iraq Stock Exchange. Method: for testing of (...) hypothesis Data from 33 listed companies on the Iraq Stock Exchange during the company's period of 2012-2022 was collected and analyzed using a multiple linear regression approach with a combination of panel data analysis. Result: Our findings indicate that Iraqi firms experience higher costs of capital due to their weak implementation of sustainability reporting. Conclusion: reporting on corporate sustainability activities can enhance reputation of companies and, by gaining legitimacy for the companies, their cost of capital is reduced. Implication: These findings can inform policymakers about the need to strengthen requirements for sustainability reporting. Also help investor to form an optimal portfolio based on the policy of companies in compliance with the sustainability reporting. (shrink)