The present study aims to examine the impact of purchasing the auditor’s opinion on financial discipline with an emphasis on corporate governance factors. From a research objective perspective, this study is applied in nature and methodologically employs a correlational design of a causal (ex post facto) type. The statistical population consists of companies listed on the Tehran Stock Exchange, from which 128 firms were selected and analyzed during the period 2018 to 2023 using a systematic elimination sampling method. The research data were collected through library studies and by extracting information from the CODAL website and companies’ financial statements. After preliminary computations in Excel, the study’s hypotheses were tested using Stata software. The findings indicate that the purchase of the auditor’s opinion has a direct and significant effect on firms’ financial discipline; however, corporate governance factors do not moderate the relationship between these two variables. Based on the results, financial discipline plays a crucial role in attracting investors and strengthening public trust in business entities. Therefore, companies that engage in purchasing the auditor’s opinion in effect take steps toward enhancing financial discipline and improving financial transparency, which are essential for their sustainability and credibility in the capital market.