This study investigated the effect of debt maturity structure on the profitability of listed non-financial firms in Nigeria, focusing on the transmission of profitability through short- and long-term leverage. Employing a quantitative research design, the study used secondary data from eighty purposively sampled non-financial firms listed on the Nigerian Exchange Group (NGX) over the period 2015–2024. Key independent variables include long-term debt ratio and short-term debt ratio, while profitability is proxied by Return on Capital Employed (ROCE), Return on Equity (ROE), and Debt/EBIT ratio. Operating cash flow is included as a control variable. Panel data analysis is conducted using the Panel-Corrected Standard Errors (PCSE) regression model to account for heteroscedasticity and cross-sectional dependence. The empirical results revealed that both long-term and short-term debt ratios exhibit largely insignificant effects on profitability, indicating that debt maturity choices are driven more by financing constraints than by performance optimization. In contrast, overall leverage intensity, measured by the debt-to-equity ratio, shows a stronger association with profitability variations and debt sustainability, highlighting that excessive leverage undermines firm performance through increased financial risk. Operating cash flow demonstrates limited direct influence on profitability. The findings suggest that in Nigerian non-financial firms, profitability transmission is less determined by the composition of debt maturity and more by capital structure discipline, earnings stability, and managerial efficiency. These insights emphasize the importance of prudent financial management and strategic leverage decisions in sustaining firm performance.