<p>This study investigates the impact of capital structure on the profitability of 15 non-banking financial institutions (NBFIs) in Bangladesh over the period from 2013 to 2024. The researcher attempts to analyse the profitability relationship with major capital structure proxies (debt-to-equity, debt-to-asset, deposit-to-asset, and equity-to-asset ratios) through OLS, Fixed Effects, Random Effects, 2SLS, and GMM methods while integrating business-specific (firm size) and macroeconomic factors. Across all estimations, DAR is consistently significant and adverse, while DR exerts a favourable and influential effect on NBFIs ROA. In contrast, the other proxy variables of capital structure (EAR, DER) found a non-substantial association with the return from NBFIs asset and equity utilisation in most model estimations. Moreover, the researcher found DR and FS consistently exerted a positive and substantial impact on the ROE of NBFIs operating in Bangladesh in most of the models. Conversely, DAR seems adversely associated with the return generated through NBFIs shareholder equity, except in the Fixed estimation. Apart from the capital structure proxy, the firm size and macroeconomic factors demonstrated mixed and limited influence on overall NBFI profitability performance. The research findings provide NBFI managers, regulators, and policymakers guidance on leverage usage, funding structure, and economic trend management. Therefore, NBFI managers need to strike an appropriate leverage level combined with strong strategic governance on capital structure management for improving the profitability of NBFIs.</p>