Financial statement comparability, as one of the qualitative characteristics of accounting information, plays a crucial role in enhancing financial transparency and improving investors’ decision-making. However, various factors, such as ownership structure, can influence the extent to which this characteristic is realized. In Iran, the substantial presence of state-owned companies in the capital market highlights the necessity of examining the impact of state ownership on financial statement comparability. This study aims to investigate the effect of state ownership on financial statement comparability, considering the moderating role of financial reporting quality. The statistical population comprises 146 companies listed on the Tehran Stock Exchange during the period 2016–2023. The research is applied in terms of purpose and descriptive–correlational in terms of methodology. Multivariate regression models and panel data techniques were employed to test the hypotheses. The findings indicate that state ownership has a positive and significant effect on financial statement comparability, contributing to the enhancement of corporate informational transparency. However, financial reporting quality (with a focus on earnings management) does not have a significant moderating effect on this relationship, suggesting that the impact of state ownership on comparability operates independently of the level of financial reporting quality. The results of this study not only enrich the academic literature but also provide practical insights for policymakers, regulatory bodies, and investors to improve corporate governance, strengthen transparency, and enhance the efficiency of the capital market.