Capital structure refers to the proportion of debt and equity employed by a firm to finance its operational activities. This study aims to examine the extent to which capital structure influences the financial profitability of telecommunication companies listed on the Vietnamese stock market. The dataset used in this study consists of 120 observations from 12 leading listed telecommunication companies in Vietnam over the period from 2014 to 2023. By employing a quantitative research approach using OLS, FEM, REM, and GLS models, the author provides empirical evidence that capital structure has a significant impact on the financial profitability of these companies. The influencing factors identified include: firm size, which has a positive relationship with the profitability of telecommunication companies; while the debt ratio, fixed assets ratio, and long-term assets ratio exhibit a negative relationship with profitability. Based on the research findings, the author proposes several recommendations to improve profitability in the telecommunications sector, such as increasing the proportion of equity in the capital structure, revaluating assets, or liquidating non-performing assets to reallocate or enhance equity capital.