The aim of the present study is to investigate the effect of profitability on the relationship between aggressive taxation and capital structure decisions in companies listed on the Tehran Stock Exchange. This study is applied in terms of purpose and descriptive correlational in nature with a multivariate linear regression analysis approach. The statistical population includes all companies listed on the Tehran Stock Exchange, and after applying sampling restrictions, 120 companies were selected over a 13-year period (2012 to 2024). The results of the hypothesis test showed that the effective tax rate has an inverse and significant relationship with capital structure, which indicates substitution between aggressive taxation and debt. Also, profitability has a positive and significant effect on capital structure. In addition, the interactive variable profitability × aggressive taxation showed a positive and significant effect on capital structure, which indicates the moderation of profitability in this relationship; in such a way that in companies with high profitability, the substitution relationship between aggressive taxation and debt is weakened and tends towards a complementary relationship. The findings of this study can be explained within the framework of equilibrium theory and non-debt tax shield theory and have important practical implications for managers.